first lieutenantBrE/ˌfɜːst lefˈtenənt/NAmE/ˌfɜːrst luːˈtenənt/nounanofficerinthenavywithresponsibilityformanagingaship, etc. undertheguidanceofthecaptain舰务官anofficerintheUSarmyandair forcejustbelowtherankofacaptain(美国陆军和空军的)中尉(informal) apersonwhoisthenextmostimportanttosb第二把手