Dictionary of Biblical Words:
The breaking of law; where there is no law, there is no transgression (Rom. 6, and 1 John 3). Sin, therefore, is not “the transgression of the law” (1 John 3:4), but “lawlessness” (R.V.). Sin existed long before the law was given, but transgression carne in with law.
Concise Bible Dictionary:
See SIN.