Origin: 1600-1700 Dutch aanslag act of striking; influenced by slaught slaughter (13-17 centuries)
1a very strong attack: onslaught on/against The rebels launched a full-scale onslaught on the capital.2a lot of criticism, opposition, etc. all at one time, which causes great problems for someone: a massive propaganda onslaughtonslaught of The president faced an onslaught of accusations.3the forceful effect of extreme weather [Origin: 1600–1700 Dutch aanslag act of striking; influenced by slaught slaughter (13–17 centuries)]