home t Julia Galdo twin [twin] –noun 1. either of two children or animals brought forth at a birth. 2. either of two persons or things closely related to or closely resembling each other. –adjective 3. being a twin or twins: twin sisters. 4. being two persons or things closely related to or closely resembling each other. 5. being one of a pair; identical: a twin bracelet; a twin peak. a b c d e f g h i j k l m n o p q r s t u v w x y z tunnel twin