Noun

1. Attractiveness or charm in dress, appearance, or manner

   Without a diploma, he relies on spiff alone to climb the corporate ladder.

2. A well-dressed man
3. A bonus or other remuneration, given for reaching a sales goal or promoting the goods of a particular manufacturer. Originally from textile retailing, a percentage given for selling off surplus or out-of-fashion stock, of which the sales person could offer part as a discount to a customer.
4. a hand-rolled marijuana cigarette; a joint
   • 2000, Leone Ross, Tasting Songs, in Dark Matter (ed. Sheree R. Thomas), p76

     She rolled a spiff for us as she spoke, sifting the ganja between her fingers...

   • 2004, Sander L. Gilman, Xun Zhou, Smoke: A Global History of Smoking, p144

     ...someone else built a spiff which he lit and gave to me...

Verb

1. (usually with up) to make spiffy (attractive, polished, or up-to-date)

   Our productivity would surely increase if we'd just spiff up this office a bit.

2. to reward (a salesperson) with a spiff.