the short, thick first digit of the human hand, differing from the other fingers in having but two phalanges; the pollex. see pollex.-to handle awkwardly.-to play with the thumbs, or with the thumbs and fingers; as, to thumb over a tune.-to soil or wear with the thumb or the fingers; to soil, or wear out, by frequent handling; also, to cover with the thumb; as, to thumb the touch-hole of a cannon.-to play with the thumb or thumbs; to play clumsily; to thrum.