late 13c., "servant who has charge of doors and admits people to a chamber, hall, etc.," from Anglo-French usser (12c.), Old French ussier, uissier "porter, doorman," from Vulgar Latin *ustiarius "doorkeeper," variant of Latin ostiarius "door-keeper," from ostium "door, entrance," from os "mouth," from PIE *os- "mouth" (see oral). Fem. form usherette is attested from 1913, American English.
1590s, "conduct, escort, admit ceremoniously," from usher (n.). Related: Ushered; ushering.