Noah Webster's Dictionary 1. (p. pr. & vb. n.) of Beset. 2. (a.) Habitually attacking, harassing, or pressing upon or about; as, a besetting sin.

Multi-Version Concordance Besetting (1 Occurrence) Hebrews 12:1 Therefore, we also having so great a cloud of witnesses set around us, every weight having put off, and the closely besetting sin, through endurance may we run the contest that is set before us, (YLT)