Petty Offense

A federal misdemeanor punishable by six months or less in prison.

Additional Sources

Answers.com

A minor crime, the maximum punishment for which is generally a fine or a short term in a prison or a house of correction.

In some states, a petty offense is a classification in addition to misdemeanor and felony. Under federal law, a petty offense is any misdemeanor, the penalty for which does not exceed imprisonment for a period of six months, a fine of not more than $5,000, or both. Since a petty offense is one that is punishable by no more than a six-month sentence, the accused is not constitutionally entitled to a jury trial, which would be in order if the accused were charged with a serious offense.

Duhaime Legal Dictionary

A minor crime and for which the punishment is usually just a small fine or short term of imprisonment.