diff --git a/modules/ca/src/client/cadef.h b/modules/ca/src/client/cadef.h
index fc94dfb6c..12861c384 100644
--- a/modules/ca/src/client/cadef.h
+++ b/modules/ca/src/client/cadef.h
@@ -559,19 +559,19 @@ LIBCA_API chid epicsStdCall ca_evid_to_chid ( evid id );
 /*
  * ca_pend_event()
  *
- * timeOut  R   wait for this delay in seconds
+ * timeout  R   wait for this delay in seconds
  */
-LIBCA_API int epicsStdCall ca_pend_event (ca_real timeOut);
+LIBCA_API int epicsStdCall ca_pend_event (ca_real timeout);
 #define ca_poll() ca_pend_event(1e-12)
 
 /*
  * ca_pend_io()
  *
- * timeOut  R   wait for this delay in seconds but return early
+ * timeout  R   wait for this delay in seconds but return early
  *              if all get requests (or search requests with null
  *              connection handler pointer have completed)
  */
-LIBCA_API int epicsStdCall ca_pend_io (ca_real timeOut);
+LIBCA_API int epicsStdCall ca_pend_io (ca_real timeout);
 
 /* calls ca_pend_io() if early is true otherwise ca_pend_event() is called */
 LIBCA_API int epicsStdCall ca_pend (ca_real timeout, int early);
diff --git a/modules/libcom/src/osi/epicsEvent.cpp b/modules/libcom/src/osi/epicsEvent.cpp
index d8b2533eb..1797366f4 100644
--- a/modules/libcom/src/osi/epicsEvent.cpp
+++ b/modules/libcom/src/osi/epicsEvent.cpp
@@ -70,9 +70,9 @@ void epicsEvent::wait ()
     }
 }
 
-bool epicsEvent::wait (double timeOut)
+bool epicsEvent::wait (double timeout)
 {
-    epicsEventStatus status = epicsEventWaitWithTimeout (this->id, timeOut);
+    epicsEventStatus status = epicsEventWaitWithTimeout (this->id, timeout);
 
     if (status == epicsEventOK) {
         return true;
diff --git a/modules/libcom/src/osi/epicsEvent.h b/modules/libcom/src/osi/epicsEvent.h
index 8cc16fe61..4fd2d338a 100644
--- a/modules/libcom/src/osi/epicsEvent.h
+++ b/modules/libcom/src/osi/epicsEvent.h
@@ -99,10 +99,12 @@ public:
      **/
     void wait ();
     /**\brief Wait for the event or until the specified timeout.
-     * \param timeOut The timeout delay in seconds.
+     * \param timeout The timeout delay in seconds. A timeout of zero is
+     * equivalent to calling tryWait(); NaN or any value too large to be
+     * represented to the target OS is equivalent to no timeout.
      * \return True if the event was triggered, False if it timed out.
      **/
-    bool wait ( double timeOut );
+    bool wait ( double timeout );
     /**\brief Similar to wait() except that if the event is currently empty the
      * call will return immediately.
      * \return True if the event was full (triggered), False if empty.
@@ -190,11 +192,13 @@ LIBCOM_API void epicsEventMustWait(epicsEventId id);
 /**\brief Wait an the event or until the specified timeout period is over.
  * \note Blocks until full or timeout.
  * \param id The event identifier.
- * \param timeOut The timeout delay in seconds.
+ * \param timeout The timeout delay in seconds. A timeout of zero is
+ * equivalent to calling epicsEventTryWait(); NaN or any value too large
+ * to be represented to the target OS is equivalent to no timeout.
  * \return Status indicator.
  **/
 LIBCOM_API epicsEventStatus epicsEventWaitWithTimeout(
-    epicsEventId id, double timeOut);
+    epicsEventId id, double timeout);
 
 /**\brief Similar to wait() except that if the event is currently empty the
  * call will return immediately with status \c epicsEventWaitTimeout.
diff --git a/modules/libcom/src/osi/epicsMessageQueue.h b/modules/libcom/src/osi/epicsMessageQueue.h
index 8240c7a5c..946195067 100644
--- a/modules/libcom/src/osi/epicsMessageQueue.h
+++ b/modules/libcom/src/osi/epicsMessageQueue.h
@@ -84,6 +84,9 @@ public:
 
     /**
      *  \brief Send a message or timeout.
+     *  \param timeout The timeout delay in seconds. A timeout of zero is
+     *  equivalent to calling trySend(); NaN or any value too large to be
+     *  represented to the target OS is equivalent to no timeout.
      *  \returns 0 if the message was sent to a receiver or queued for
      *  future delivery.
      *  \returns -1 if the timeout was reached before the
@@ -124,12 +127,16 @@ public:
     int receive ( void *message, unsigned int size );
 
     /**
-     *  \brief Wait for a message to be queued.
-     *  Wait up to \p timeout seconds for a message to be sent if the queue
-     *  is empty, then move the first message to the specified location.
+     *  \brief Wait for and fetch the next message.
+     *  \param timeout The timeout delay in seconds. A timeout of zero is
+     *  equivalent to calling tryReceive(); NaN or any value too large to
+     *  be represented to the target OS is equivalent to no timeout.
      *
-     *  If the received message is larger than the specified
-     *  messageBufferSize it may either return -1, or truncate the
+     *  Waits up to \p timeout seconds for a message to arrive if the queue
+     *  is empty, then moves the first message to the specified location.
+     *
+     *  If the received message is larger than the specified message size
+     *  the implementation may either return -1, or truncate the
      *  message. It is most efficient if the messageBufferSize is equal
      *  to the maximumMessageSize with which the message queue was
      *  created.
diff --git a/modules/libcom/src/osi/os/RTEMS-posix/osdEvent.c b/modules/libcom/src/osi/os/RTEMS-posix/osdEvent.c
index abd9a8e9a..8c2c81e3e 100644
--- a/modules/libcom/src/osi/os/RTEMS-posix/osdEvent.c
+++ b/modules/libcom/src/osi/os/RTEMS-posix/osdEvent.c
@@ -62,7 +62,7 @@ epicsEventWait(epicsEventId pSem)
 }
 
 LIBCOM_API epicsEventStatus
-epicsEventWaitWithTimeout(epicsEventId pSem, double timeOut)
+epicsEventWaitWithTimeout(epicsEventId pSem, double timeout)
 {
     int sc;
     rtems_interval delay;
@@ -71,22 +71,22 @@ epicsEventWaitWithTimeout(epicsEventId pSem, double timeOut)
     if (!rate)
         return epicsEventError;
 
-    if (timeOut <= 0.0) {
+    if (timeout <= 0.0) {
         sc = rtems_binary_semaphore_try_wait(&pSem->rbs);
         if (!sc)
             return epicsEventOK;
         else
             return epicsEventWaitTimeout;
     }
-    else if (timeOut < (double) UINT32_MAX / rate) {
-        delay = timeOut * rate;
+    else if (timeout < (double) UINT32_MAX / rate) {
+        delay = timeout * rate;
         if (delay == 0) {
-            /* 0 < timeOut < 1/rate; round up */
+            /* 0 < timeout < 1/rate; round up */
             delay = 1;
         }
     }
     else {
-        /* timeOut is NaN or too big to represent; wait forever */
+        /* timeout is NaN or too big to represent; wait forever */
         delay = RTEMS_NO_TIMEOUT;
     }
 
diff --git a/modules/libcom/src/osi/os/RTEMS-score/osdEvent.c b/modules/libcom/src/osi/os/RTEMS-score/osdEvent.c
index 7cad7b9b8..d81538c7f 100644
--- a/modules/libcom/src/osi/os/RTEMS-score/osdEvent.c
+++ b/modules/libcom/src/osi/os/RTEMS-score/osdEvent.c
@@ -122,17 +122,17 @@ epicsEventWait(epicsEventId id)
 }
 
 epicsEventStatus
-epicsEventWaitWithTimeout(epicsEventId id, double timeOut)
+epicsEventWaitWithTimeout(epicsEventId id, double timeout)
 {
     rtems_id sid = (rtems_id)id;
     rtems_status_code sc;
     rtems_interval delay;
     extern double rtemsTicksPerSecond_double;
 
-    if (timeOut <= 0.0)
+    if (timeout <= 0.0)
         return epicsEventTryWait(id);
     SEMSTAT(1)
-    delay = timeOut * rtemsTicksPerSecond_double;
+    delay = timeout * rtemsTicksPerSecond_double;
     if (delay == 0)
         delay++;
     sc = rtems_semaphore_obtain (sid, RTEMS_WAIT, delay);
diff --git a/modules/libcom/src/osi/os/WIN32/osdEvent.c b/modules/libcom/src/osi/os/WIN32/osdEvent.c
index 62117cb16..6eb64d4ca 100644
--- a/modules/libcom/src/osi/os/WIN32/osdEvent.c
+++ b/modules/libcom/src/osi/os/WIN32/osdEvent.c
@@ -90,7 +90,7 @@ LIBCOM_API epicsEventStatus epicsEventWait ( epicsEventId pSem )
  * epicsEventWaitWithTimeout ()
  */
 LIBCOM_API epicsEventStatus epicsEventWaitWithTimeout (
-    epicsEventId pSem, double timeOut )
+    epicsEventId pSem, double timeout )
 {
     /* waitable timers use 100 nanosecond intervals, like FILETIME */
     static const unsigned ivalPerSec = 10000000u; /* number of 100ns intervals per second */
@@ -101,17 +101,17 @@ LIBCOM_API epicsEventStatus epicsEventWaitWithTimeout (
     HANDLE timer;
     LONGLONG nIvals;  /* number of intervals */
 
-    if ( timeOut <= 0.0 ) {
+    if ( timeout <= 0.0 ) {
         tmo.QuadPart = 0u;
     }
-    else if ( timeOut >= INFINITE / mSecPerSec  ) {
+    else if ( timeout >= INFINITE / mSecPerSec  ) {
         /* we need to apply a maximum wait time to stop an overflow. We choose (INFINITE - 1) milliseconds,
            to be compatible with previous WaitForSingleObject() implementation */    
         nIvals = (LONGLONG)(INFINITE - 1) * (ivalPerSec / mSecPerSec);
         tmo.QuadPart = -nIvals;  /* negative value means a relative time offset for timer */
     }
     else {
-        nIvals = (LONGLONG)(timeOut * ivalPerSec + 0.999999);
+        nIvals = (LONGLONG)(timeout * ivalPerSec + 0.999999);
         tmo.QuadPart = -nIvals;
     }
 
diff --git a/modules/libcom/src/osi/os/vxWorks/osdEvent.c b/modules/libcom/src/osi/os/vxWorks/osdEvent.c
index dc139432c..38c4d1806 100644
--- a/modules/libcom/src/osi/os/vxWorks/osdEvent.c
+++ b/modules/libcom/src/osi/os/vxWorks/osdEvent.c
@@ -34,24 +34,24 @@ void epicsEventDestroy(epicsEventId id)
     semDelete((SEM_ID)id);
 }
 
-epicsEventStatus epicsEventWaitWithTimeout(epicsEventId id, double timeOut)
+epicsEventStatus epicsEventWaitWithTimeout(epicsEventId id, double timeout)
 {
     int rate = sysClkRateGet();
     int status;
     int ticks;
 
-    if (timeOut <= 0.0) {
+    if (timeout <= 0.0) {
         ticks = 0;
     }
-    else if (timeOut < (double) INT_MAX / rate) {
-        ticks = timeOut * rate;
+    else if (timeout < (double) INT_MAX / rate) {
+        ticks = timeout * rate;
         if (ticks == 0) {
-            /* 0 < timeOut < 1/rate; round up */
+            /* 0 < timeout < 1/rate; round up */
             ticks = 1;
         }
     }
     else {
-        /* timeOut is NaN or too big to represent in ticks */
+        /* timeout is NaN or too big to represent in ticks */
         ticks = WAIT_FOREVER;
     }
     status = semTake((SEM_ID)id, ticks);
diff --git a/modules/libcom/src/osi/os/vxWorks/osdMessageQueue.cpp b/modules/libcom/src/osi/os/vxWorks/osdMessageQueue.cpp
index d06952209..fe3ef1563 100644
--- a/modules/libcom/src/osi/os/vxWorks/osdMessageQueue.cpp
+++ b/modules/libcom/src/osi/os/vxWorks/osdMessageQueue.cpp
@@ -30,15 +30,15 @@ LIBCOM_API int epicsStdCall epicsMessageQueueSendWithTimeout(
     if (timeout <= 0.0) {
         ticks = 0;
     }
-    else if (timeOut < (double) INT_MAX / rate) {
+    else if (timeout < (double) INT_MAX / rate) {
         ticks = timeout * rate;
         if (ticks == 0) {
-            /* 0 < timeOut < 1/rate; round up */
+            /* 0 < timeout < 1/rate; round up */
             ticks = 1;
         }
     }
     else {
-        /* timeOut is NaN or too big to represent in ticks */
+        /* timeout is NaN or too big to represent in ticks */
         ticks = WAIT_FOREVER;
     }
 
@@ -57,15 +57,15 @@ LIBCOM_API int epicsStdCall epicsMessageQueueReceiveWithTimeout(
     if (timeout <= 0.0) {
         ticks = 0;
     }
-    else if (timeOut < (double) INT_MAX / rate) {
+    else if (timeout < (double) INT_MAX / rate) {
         ticks = timeout * rate;
         if (ticks == 0) {
-            /* 0 < timeOut < 1/rate, round up */
+            /* 0 < timeout < 1/rate, round up */
             ticks = 1;
         }
     }
     else {
-        /* timeOut is NaN or too big to represent in ticks */
+        /* timeout is NaN or too big to represent in ticks */
         ticks = WAIT_FOREVER;
     }