'trader' originates from English, specifically formed from the noun 'trade' + the agent suffix '-er', where 'trade' referred to an occupation or course of activity and '-er' meant 'one who does'.

'trade' developed in Middle English from earlier Germanic roots (related to Old English 'tredan'/'tred' meaning 'to tread' or 'a track'), and the agent-forming '-er' attached to create 'trader' in Early Modern English; this evolved into the modern English 'trader'.

Initially associated with a course of action or occupation (a 'track' or 'practice'), the term shifted to the commerce sense 'buying and selling', and 'trader' came to mean 'one who buys and sells' (goods or financial instruments).