See second-in-command for more second in commandBrE /ˌsekənd ɪn kəˈmɑːnd/ 🔊NAmE /ˌsekənd ɪn kəˈmænd/ 🔊 nouna person who has the second highest rank in a group and takes charge when the leader is not there 副指挥官;二号人物