Plural of crower; multiple roosters, or multiple people who boast or crow about their achievements.
From 'crower' (one who crows) + '-s' (plural). The formation follows standard English pluralization of agent nouns derived from verbs.
Historically, competitive farms with multiple roosters would literally have 'crowers' trying to out-crow each other at dawn—and the term extended beautifully to people who boast competitively.
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