The Collaborative International Dictionary of English v.0.48:

Scapegrace \Scape"grace`\, n.
   A graceless, unprincipled person; one who is wild and
   reckless. --Beaconsfield.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scapegrace
    n 1: a reckless and unprincipled reprobate [syn: scapegrace,
         black sheep]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "scapegrace":
   backslider, bad boy, bad egg, bad lot, black sheep, booger,
   buffoon, bugger, cutup, degenerate, devil, elf, enfant terrible,
   fallen angel, funmaker, good-for-nothing, hood, hoodlum, hooligan,
   imp, joker, jokester, knave, lecher, little devil, little monkey,
   little rascal, lost sheep, lost soul, minx, mischief,
   mischief-maker, miscreant, no-good, pervert, pimp, pixie,
   practical joker, prankster, profligate, puck, rapscallion, rascal,
   recidivist, recreant, reprobate, rogue, rounder, rowdy, ruffian,
   scamp, sorry lot, trollop, wag, waster, whore