Home›Browse›A›anvil cloudanvil cloudOur editors are putting together more complete content — check back in about 20 minutesanvil cloudanvil cloud — nounnoun1. a flat-topped thunderstorm cloud that spreads out like an anvil1.nounDefinitiona flat-topped thunderstorm cloud that spreads out like an anvilExampleThe sky darkened as an anvil cloud formed above the plains.