menhaden /mɛn.heɪ.d(ə)n/ noun1 •Any of several species of fish in the genera Brevoortia and Ethmidium, used for fish meal, fish oil, fertilizer, and bait.Divergence of the largescaled menhadens from the small-scaled menhadens resulted either from geographic isolation or different habitat preferences. — 1970 formsmenhadens