'self-restrainedly' originates from the combination of 'self-' and 'restrained,' where 'self-' refers to one's own person and 'restrained' means controlled or held back.

'self-restrained' evolved from the Middle English word 'restreyned,' which came from the Old French 'restreindre,' and eventually became the modern English word 'restrained.'

Initially, it meant 'to hold back or control oneself,' and this meaning has largely remained the same in modern usage.