'reaction-caused' is a compound word formed from 'reaction' and 'caused'. 'Reaction' originates from Latin 'reactio', meaning 'a response', and 'caused' is the past participle of 'cause', from Latin 'causa', meaning 'reason'.

'Reaction' evolved from the Latin 'reactio' through Old French 'reaction', while 'caused' comes from the Latin 'causa' through Old French 'causer'.

Initially, 'reaction' meant 'a response to an action', and 'caused' meant 'brought about'. Together, they describe something brought about by a response.