Definition of "lieutenant" in English

noun

1. (military) The lowest junior commissioned officer rank(s) in many military forces, often Army and Marines.

2. A person who manages or executes the plans and directives of another, more senior person; a manager to their director.

3. The second-in-command (2IC) of a group.

adjective

1. A military grade that is junior to the grade the adjective modifies: lieutenant colonel, lieutenant general, lieutenant commander.