As a noun or an adjective, workout is one word. As a verb, it’s two words—work out. So, for instance, when it’s workout time, you start your workout, work out for a while, and stop.
Work out is just one of many phrasal verbs with corresponding one word forms that function as nouns and adjectives. The one-word forms are sometimes hyphenated (e.g., work-out), but more often completely compounded. These forms never catch on as verbs in edited writing, though they are often erroneously treated as verbs in more informal contexts.
Heisman Trophy winner Cam Newton is expected to hold a workout in front of the media on Feb. 10 in San Diego. [CBS42]
So if this appeal doesn’t work out, we are happy to inform you that there’s a mayoral election going on in Baltimore, too. [Baltimore Sun]
The Liberal leader was also sighted squeezing in a workout at the Parliament House gym on Monday. [The Daily Telegraph]
All world-class athletes now work out with weights. [Bloomberg]
Then again, Wilson is said to have the most intense workout regimen on the team. [San Francisco Chronicle]