IPA: /aʊtˈnʌmbər/
KK: /aʊtˈnʌmbər/
To have a greater number of people or things than another group.
In the last election, the younger voters outnumbered the older ones.
Past: outnumbered
Past Participle: outnumbered
Outnumber → It is formed from "out-" (meaning beyond or more than) and "number" (from Old French *nombre*, meaning a count or quantity). The word "outnumber" means to have a greater number than someone or something else.
Think of having a count that is 'beyond' ('out-') another count — that's why outnumber means to have more in quantity.