Entry 1 sense Webster, 1913 Biro · IPA /ˈbaɪ.ɹəʊ/ 01 n. a pen with small metal ball as point of transfer of ink to paper; same as ballpoint pen. 1. a pen with small metal ball as point of transfer of ink to paper; same as ballpoint pen. See: ballpoint pen Syn. ballpoint, ballpoint pen, ballpen.