'Practical joke' definitions:

Definition of 'practical joke'

noun

A prank or trick played on a person (especially one intended to make the victim appear foolish)

From: GCIDE

Practical \Prac"ti*cal\, a. [L. practicus active, Gr. ? fit for doing or performing, practical, active, fr. ? to do, work, effect: cf. F. pratique, formerly also practique. Cf. Pragmatic, Practice.]
1. Of or pertaining to practice or action. [1913 Webster]
2. Capable of being turned to use or account; useful, in distinction from ideal or theoretical; as, practical chemistry. "Man's practical understanding." --South. "For all practical purposes." --Macaulay. [1913 Webster]
3. Evincing practice or skill; capable of applying knowledge to some useful end; as, a practical man; a practical mind. [1913 Webster]
4. Derived from practice; as, practical skill. [1913 Webster]
Practical joke, a joke put in practice; a joke the fun of which consists in something done, in distinction from something said; esp., a trick played upon a person. [1913 Webster]

From: GCIDE

Joke \Joke\, n. [L. jocus. Cf Jeopardy, Jocular, Juggler.] [1913 Webster]
1. Something said for the sake of exciting a laugh; something witty or sportive (commonly indicating more of hilarity or humor than jest); a jest; a witticism; as, to crack good-natured jokes. [1913 Webster]
And gentle dullness ever loves a joke. --Pope. [1913 Webster]
Or witty joke our airy senses moves To pleasant laughter. --Gay. [1913 Webster]
2. Something not said seriously, or not actually meant; something done in sport. [1913 Webster]
Inclose whole downs in walls, 't is all a joke. --Pope. [1913 Webster]
In joke, in jest; sportively; not meant seriously.
Practical joke. See under Practical. [1913 Webster]