'hearten' originates from English, specifically from the noun 'heart' plus the verb-forming suffix '-en', where 'heart' meant 'the physical heart' and figuratively 'courage' or 'feeling', and '-en' meant 'to make' (to cause to be).

'heart' comes from Old English 'heorte' (meaning 'heart' both physical organ and seat of feeling); Middle English formed causative verbs by adding '-en', producing forms like 'hearten', which developed into the modern verb 'hearten'.

Initially it carried the literal and figurative sense of 'make (someone) of heart' (i.e., strengthen the heart or courage); over time it evolved into the current meaning 'to encourage or give hope', a development that largely preserved the figurative sense.