plural lieutenants
1
: an officer in the army, navy, or air force with a fairly low rank
He was promoted to the rank of lieutenant.
Good morning, Lieutenant Smith.
—abbr. Lt.
2
US
: an officer in a fire or police department who has a rank below a captain
3
: an assistant to another, more powerful person : a person who represents and works for someone else
She has her best lieutenants working on a proposal.
one of the mobster's most loyal lieutenants
Cite this Entry
“Lieutenant.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/lieutenant. Accessed 16 Apr. 2026.
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