The Collaborative International Dictionary of English v.0.48:

Infraction \In*frac"tion\, n. [L. infractio: cf. F. infraction.]
   The act of infracting or breaking; breach; violation;
   nonobservance; infringement; as, an infraction of a treaty,
   compact, rule, or law. --I. Watts.
   [1913 Webster]

WordNet (r) 3.0 (2006):

infraction
    n 1: a crime less serious than a felony [syn: misdemeanor,
         misdemeanour, infraction, violation, infringement]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "infraction":
   aberrance, aberrancy, abnormality, bad faith, breach,
   breach of contract, breach of faith, breach of law,
   breach of privilege, breach of promise, breach of trust, breaking,
   civil disobedience, contravention, crime, criminality, delinquency,
   deviance, deviancy, disobedience, encroachment, error, faux pas,
   frowardness, illegality, improperness, impropriety,
   inappropriateness, incorrectness, incursion, indecorousness,
   indecorum, indiscipline, indocility, infringement, inroad,
   insubordination, intractability, intrusion, lapse, lawbreaking,
   lawlessness, naughtiness, noncompliance, nonconformity,
   noncooperation, nonobedience, offense, overstepping,
   passive resistance, recusancy, sin, sinfulness, slip,
   transgression, trespass, trespassing, uncooperativeness,
   unduteousness, undutifulness, unfitness, unfittingness,
   unlawfulness, unrighteousness, unseemliness, unsubmissiveness,
   unsuitability, usurpation, violation, violation of law,
   waywardness, wickedness, willful disobedience, wrong, wrongfulness,
   wrongness



Bouvier's Law Dictionary, Revised 6th Ed (1856):

INFRACTION. The breach of a law or agreement; the violation of a compact. In
the French law this is the generic expression to designate all actions which
are punishable by the code of France.