...and the Israelite woman's son blasphemed the Name, and cursed. Then they brought him to Moses. His mother's name was Shelomith, the daughter of Dibri, of the tribe of Dan.
Leviticus 24:11

Blasphemy means cursing or insulting, but there are a few words translated "blasphemy" in the Old Testament, so the meaning can be cloudy. Speaking or misappropriating God's name isn't necessarily blasphemy, but cursing it always is. The man in Leviticus 24:11 both misused the name of YHVH and cursed it. He covered all the bases.

It was a crime against the entire community because the sanctity of God's name is vital for community health, so the whole congregation participated in the blasphemer's stoning. They laid hands on his head like he was a sacrificial animal. They were about to take a man's life and so they passed the bloodguilt of their actions and the atoning effect of the blood about to be shed onto the head of the convicted man.