A lieutenant (UK: /lɛfˈtɛnənt/ lef-TEN-ənt, US: /luːˈtɛnənt/ loo-TEN-ənt; abbreviated Lt., Lt, LT, Lieut and similar) is a commissioned officer rank in the armed forces of many nations. The meaning of lieutenant differs in different militaries (see comparative military ranks), but it is often subdivided into senior (first lieutenant) and junior (second lieutenant and even third lieutenant) ranks. In navies, it is often equivalent to the army rank of captain; it may also indicate a particular post rather than a rank. The rank is also used in fire services, emergency medical services, security services and police forces.