The Collaborative International Dictionary of English v.0.48:

Truant \Tru"ant\, n. [F. truand, OF. truant, a vagrant, beggar;
   of Celtic origin; cf. W. tru, truan, wretched, miserable,
   truan a wretch, Ir. trogha miserable, Gael. truaghan a poor,
   distressed, or wretched creature, truagh wretched.]
   One who stays away from business or any duty; especially, one
   who stays out of school without leave; an idler; a loiterer;
   a shirk. --Dryden.
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         I have a truant been to chivalry.        --Shak.
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   To play truant, to stray away; to loiter; especially, to
      stay out of school without leave. --Sir T. Browne
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