The senior grade of lieutenant is known as first lieutenant in the United States, and as lieutenant in the United Kingdom and the rest of the English-speaking world.

In English, lieutenant is best known as a military title, but the word is still sometimes used in its original meaning to refer to a person who acts in lieu of someone else.

Lieutenant, company grade officer, the lowest rank of commissioned officer in most armies of the world. The lieutenant normally commands a small tactical unit such as a platoon.

LIEUTENANT definition: 1. (the title of) an officer of middle rank in the armed forces: 2. (the title of) an officer of…. Learn more.

Definition of lieutenant noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Military. first lieutenant. second lieutenant. U.S. Navy. a commissioned officer ranking between lieutenant junior grade and lieutenant commander. a person who holds an office, civil or military, in …

Dec 22, 2025 · (military, US) In the US Army, Air Force and Marines, holding the rank above second lieutenant and below captain. Both ranks may be referred to as " lieutenant" or as the complete forms …