unsparing

adjective

1. not sparing; liberal or profuse; excessive.
2. unmerciful; harsh; severe.

adjective

1. not sparing or frugal; lavish; profuse
2. showing harshness or severity; unmerciful

adj.“showing no mercy,” 1580s, from un- (1) “not” + sparing (see spare (v.)). Related: Unsparingly.