1An attack or onset of disease or other misfortune. In Old English perhaps: specifically †a swelling (obsolete). Now: specifically (Scottish) a sudden cold or fever.
2Generally. An attack, assault, or onslaught.
Old English; earliest use found in Bald's Leechbook. Cognate with or formed similarly to Middle Dutch aenval (Dutch aanval), Middle Low German anval, German Anfall from the Germanic base of on- + the Germanic base of fall; Old Swedish anfal (Swedish anfall), Danish anfald are after Middle Low German.