Definitions
1.verb(usually with up or out) To make spiffy (attractive, polished, or up-to-date)
2.verbTo reward (a salesperson) with a spiff or bonus.
3.verbTo attach a spiff or bonus to the selling of (a product)
4.verbTo throw; to heave."I spiffed the turf over the edge and it went straight through the window and hit the officer."
5.adjectiveVery good, excellent."We're having a picnic at the races — how spiffing!"
6.adjectiveSmart or appealing in dress or appearance."I say, that outfit is simply spiffing."