Puckish

Puckish \PUHK-ish\ , adjective;]
1. Whimsical; mischievious; impish

This word is first attested in 1874 and is a combination of puck + -ish (duh).

Not so 'duh':
There are two puck words in the English language. One is used in hockey, the other means "mischevious fairy". I'm going to go out on a limb here and assume that puckish is based off the latter.
That puck comes from "A Midsummer Night's Dream" and is probably adapted from pouke, which dates to the 1300's and means "devil, evil spirit". Pouke comes from Old English puca of unknown origin. Capitalizing this word dates to the 16th century, but that is relatively obvious since Shakespeare wrote that play in the 1590's.

Now, there is a word related to puck that I find interesting: pug. This word dates to the 1560's, but it had nothing to do with dogs until about 1749. Actually, pug has meant almost everything under the sun. It was "a bargeman" in the 1590's, "a harlot" in the 1600's, "sprite, imp" around 1610, "miniature dog" around 1794, and "upper servant in a great house" around 1847. Pug-nose dates to around 1778 and is based on either the dog or monkey reference. How a word takes on so many senses is beyond me.

The suffix -ish is a 'true English' morpheme that comes from Old English -isc. It is a pretty common Germanic affix and a cognate of the Greek diminutive suffix -iskos. The colloquial practice of adding it to an hour to denote approximation (e.g. at 7:57 it is 'eight-ish') is first attested in 1916.

Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Tuesday, March 8
Etymologies come from the Oxford English Dictionary and/or Etymonline.com