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

See also: generous, inclement, unsparingly

• overnight bag
• overnight case
• overnighter
• overpass
• overpay
• overpayment
• overplay
• overplus
• overpopulate
• overpopulation
• overpower
• overpowering
• overpoweringly
• overpraise
• overpressure
• overprice
• overpriced
• overprint
• overproduce
• overproduction
• overproof
• overprotect
• overprotection
• overprotective
• overproud