arietiform UK /ˌɛəɹiˈɛtɪfɔːm/US /ˌɛɹiˈɛtɪfɔɹm/ adjective1 •Having the shape of a ram's head or of the astrological symbol of Aries, ⟨♈︎⟩.The arietiform marks become broader and more prominent.