Why is the ninth month called September?
late 15c. (in astronomy), present participle adjective from command (v.). Meaning "nobly dignified" is from 1590s. Meaning "dominant by virtue of size or position" is from 1630s. Related: Commandingly (mid-15c.).
c.1300, from Old French comander "to order, enjoin, entrust" (12c.), from Vulgar Latin *commandare, from Latin commendare "to recommend, entrust to" (see commend), altered by influence of Latin mandare "to commit, entrust" (see mandate (n.)). Replaced Old English bebeodan. Related: Commanded; commanding.
c.1400, "order, command," from Old French comand (14c.), from comander (see command (v.)). Meaning "control, authority" is from mid-15c.