say it: loo-TEN-uhnt
lieutenant is a noun meaning "a commissioned military officer". It carries 4 recorded senses.
a commissioned military officer
military
an officer in a police force
an assistant with power to act when his superior is absent
an officer holding a commissioned rank in the United States Navy or the United States Coast Guard; below lieutenant commander and above lieutenant junior grade
military
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for lieutenant come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.