"showing no mercy," 1580s, from un- (1) "not" + sparing, attested from late 14c. as a present-participle adjective from spare (v.). Meaning "profuse" is from 1660s. Related: Unsparingly.
unsparing generosity
an unsparing critic
unsolved
unsophisticated
unsorted
unsought
unsound
unsparing
unspeakable
unspoiled
unspoken
unsporting
unsportsmanlike
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