Synonyms for quacks:

ululations (noun)

ululations, twits.

ululates (verb)

bleats, trills, snorts, squeals, squawks, chatters, honks, Whinnies, bellows, neighs, Cries, ululates, warbles, snarls, caws, coos, roars, gobbles, howls, meows, growls, calls, cuckoos, chirps, bawls, Crows, clucks, yelps, brays, purrs, Bays, hoots, mews, barks, cackles, moos, grunts.

Usage examples for quacks:

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Korean Velvet Grass

Mascarene Grass, Zoysia Tenuifolia, Mascarene Grass, Zoysia Tenuifolia.