English 'adjust' from French 'ajuster' (to make right), from Latin 'iūstus' (just), from 'iūs' (right, law).
To alter or move something slightly in order to achieve the desired fit, appearance, or result; to adapt to new conditions.
From French 'ajuster' (to make conform, to fit, to arrange), from Old French 'ajoster' (to join, to add, to place side by side), from 'a-' (to, from Latin 'ad-') + 'juste' (right, exact, proper), from Latin 'iūstus' (just, righteous, lawful, legitimate), from 'iūs' (right, law, justice), from PIE *h₂yew- (law, vital force, perhaps originally 'sacred formula'). The original French sense was 'to make just or right' — to bring something into conformity with a standard — which evolved into the broader 'to bring into proper position or alignment.' The English spelling
To 'adjust' something literally means to 'make it just' — to bring it into conformity with what is right or proper. The word shares its root with 'justice,' 'jury,' 'judge,' and 'jurisdiction.' When you adjust a dial, you are etymologically making it 'righteous.'