Post-captain \Post"-cap`tain\, n.
A captain of a war vessel whose name appeared, or was
"posted," in the seniority list of the British navy, as
distinguished from a commander whose name was not so posted.
The term was also used in the United States navy; but no such
commission as post-captain was ever recognized in either
service, and the term has fallen into disuse.
[1913 Webster]