1. Very generous
   "unsparing generosity"
   - lavish, munificent, overgenerous, too-generous, unstinted, unstinting 
2. Not forbearing; ruthless
   "an unsparing critic"

See also: generous, inclement, unsparingly

• inundate
• inundated
• inundation
• inure
• inured
• inurement
• inurn
• inutile
• inutility
• invade
• invader
• invading
• invaginate
• invagination
• invalid
• invalidate
• invalidated
• invalidating
• invalidation
• invalidator
• invalidism
• invalidity
• invalidly
• invalidness
• invaluable