'harmonist' originates from English, specifically formed from the word 'harmony' with the agent suffix '-ist', where 'harmony' ultimately came from Greek 'harmonia' meaning 'joint, agreement'.

'harmony' changed from Old French 'harmonie' and Latin 'harmonia', which came from Greek 'harmonia'; the English agent-forming suffix '-ist' was later added to create 'harmonist'.

Initially, it meant 'one skilled in musical harmony', but over time it has also been used more broadly to mean 'one who promotes social or interpersonal concord'.