course of action is a noun meaning "a mode of action". It carries one recorded sense.
a mode of action
“if you persist in that course you will surely fail”
“once a nation is embarked on a course of action it becomes extremely difficult for any retraction to take place”
Definitions, synonyms and semantic relations for course of action come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.