-function suspends execution of the calling process until either
-.Fa microseconds
-microseconds have elapsed or a signal is delivered to the process and its
-action is to invoke a signal-catching function or to terminate the
-process.
-System activity may lengthen the sleep by an indeterminate amount.
+function suspends execution of the calling thread until either
+.Fa useconds
+microseconds have elapsed
+or a signal is delivered to the thread whose action
+is to invoke a signal-catching function
+or to terminate the thread or process.
+The actual time slept may be longer, due to system latencies
+and possible limitations in the timer resolution of the hardware.