temperance

Temperance comes through Anglo-Norman temperance from Latin temperantia, meaning moderation, sobriety, discretion, or self-control. That noun traces back to temperans, the present participle of temperare, 'to moderate.'

The facts given don't describe a shift in meaning — temperantia already carried the sense of moderation and self-control in Latin, and English temperance kept that core sense.

English temper comes from the same root, temperare, making it a close relative built straight from the same Latin verb.