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to fail to keep possession of something
She lost her keys and couldn't get into her house.
She couldn't find her keys and was locked out.
Often used with 'to' to indicate the thing lost.
to fail to win a game or competition
The team lost the championship by one point.
They were defeated in the final game.
Common in sports contexts.
to suffer a disadvantage or setback
He lost his job due to the company's downsizing.
He was fired because the company reduced staff.
Can imply a negative outcome.
Remember that 'lose' is a verb, not an adjective. The adjective form is 'loose'.
'Lose' is an irregular verb: lose (present), lost (past), lost (past participle).
From Middle English 'losen', from Old English 'losian', meaning 'to perish, destroy, or lose'. Related to Old Norse 'losa' and Old High German 'lōsan'.
Often confused with 'loose' (not tight). 'Lose' is a verb, while 'loose' is an adjective.