tattoo

The skin-marking sense comes from earlier tattaow/tattow, borrowed from a Polynesian language such as Samoan tatau, meaning 'to tap, to strike.' A separate military sense, meaning a drum or bugle signal, comes from earlier tap-to, borrowed from Dutch taptoe, literally 'tap shut' (tap + toe), the signal to close the taps on beer casks at day's end. A third, unrelated sense for a small pony comes from Hindi टट्टू (ṭaṭṭū).

The skin-marking word traveled from Polynesian languages into English sailors' vocabulary largely unchanged in meaning. The military sense shifted from a literal instruction to shut off beer taps into a general term for the signal itself, and eventually for the ceremonial display built around it.

The military sense of tattoo shares its root with the English word 'tap,' both tracing back to the Dutch instruction to shut off a cask's tap.