The word 一犯再犯 is formed by sequentially combining the character 一 (meaning "one" or "once") with 犯 (meaning "to commit" an offense), followed by 再 (meaning "again") and a repetition of 犯, where 一 modifies the first 犯 to indicate "committing once", and 再 modifies the second 犯 to indicate "committing again", resulting in a phrase that literally means "once commit, again commit" and conveys the concept of repeated offenses.