lieutenants are often equivalent to the army rank of captain; in other navies, the lieutenants are usually equal to their army counterparts.

Lieutenant may also appear as part of a title used in various other organisations with a codified command structure. It often designates someone who is "second-in-command", and as such, may precede the name of the rank directly above it. For example, a "lieutenant master" is likely to be second-in-command