The Collaborative International Dictionary
Unsparingness
Unsparing \Un*spar"ing\, a. [Pref. un- not + sparing, p. pr. of spare.]
Not sparing; not parsimonious; liberal; profuse.
--Burke.Not merciful or forgiving. [R.]
--Milton. [1913 Webster] -- Un*spar"ing*ly, adv. -- Un*spar"ing*ness, n.
Wiktionary
unsparingness
n. The state of being unsparing.