know-it-all 
(nōĭt-ôl′)
(nōĭt-ôl′)n.
Informal
Informal
One who acts as if he or she knows everything, as by offering unsolicited advice or rejecting others' suggestions.
know-it-all′ adj.
- peroxyacetyl nitrate
- perp
- perp.
- perpend
- perpendicular
- perpendicularity
- perpendicularly
- perpetrate
- perpetration
- perpetrator
- perpetual
- perpetual calendar
- perpetually
- perpetual motion
- perpetuance
- perpetuate
- perpetuation
- perpetuator
- perpetuity
- perphenazine
- Perpignan
- perplex
- perplexed
- perplexedly
- perplexingly