venial sin

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An offense that is judged to be minor or committed without deliberate intent and thus does not estrange the soul from the grace of God.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Roman Catholic theology A sin that is not a mortal sin; a sin that is not grave, or was not deliberate or was committed without a full understanding of the consequences.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a pardonable sin regarded as entailing only a partial loss of grace