WSC Q.14: What is sin?
Sin is any want of conformity unto, or transgression of, the law of God. (1 John 3:4)
WLC Q.24: What is sin?
Sin is any want of conformity unto, or transgression of, any law of God, given as a rule to the reasonable creature. (1 John 3:4, Gal. 3:10,12)