“Sin” is any action, thought, or word that does not honor God. Sinning is disobeying God. Sin is also when someone does not do what God wants them to do (see: James 4:17). A “sinner” is someone who sins (see: Romans 3:23). Anything that does not honor God is “sinful.”
“Sins” are the individual things someone does that do not honor God. Examples of sins are murder and adultery (see: Exodus 20:13-14; Matthew 5:21-30). The word “sin” also means “sinful nature” (see: Romans 7:14-20). For a person to have a sinful nature means that he is completely unable to do anything to honor God.
There are many words in the Bible that mean “sin.”