adj

• (archaic or regional, Yorkshire) Neat, smartly dressed, attractive.
  "“Hah spiff he is to dāay!—he mud be bown tul a wedding!” “He’s spiff eniff for’t!”"

noun

• (uncountable) Attractiveness or charm in dress, appearance, or manner.
  "Without a diploma, he relies on spiff alone to climb the corporate ladder."
• (countable, archaic, slang) A well-dressed man; a swell.
• (countable, commerce, slang) 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.
  "The strongly-recommended piece of cloth was, in the conventional language of the drapery trade, a “spiff” in other words, a remnant of an old stock which had been lying by unsold for three or four years, perhaps longer, and had faded through keeping, like other beautiful things, thereby decreasing in value."
• (countable, colloquial, Jamaica) Alternative form of spliff (“hand-rolled marijuana cigarette”).
  "She rolled a spiff for us as she spoke, sifting the ganja between her fingers […]"

verb

• (transitive, informal) (usually with up or out) To make spiffy (attractive, polished, or up-to-date)
  "Oh, but we flatter ourselves that we are spiffed out; at all events, we've got our best dresses on."
• (transitive, commerce, slang) To reward (a salesperson) with a spiff or bonus.
  "It is my confirmed belief that, spiffed or not, the salesman is the consumer's best-qualified and best- informed source of assistance in matters of component selection."
• (transitive, commerce, slang) To attach a spiff or bonus to the selling of (a product)
  "It wasn't my fault if the blamed old store caught fire and gave me a chance to help Ferguson move out some of the stuff that has been 'spiffed' till it looks like red ink had been spilled all over the price-tags."