'dealings' comes from the noun 'dealing', which is formed from the verb 'deal' + suffix '-ing'. The verb 'deal' in modern English comes via Middle English from Old English 'dǣlan' meaning 'to divide, distribute'.

'deal' changed from Old English 'dǣlan' (to divide) into Middle English 'delen'/'delen' with senses of distributing and negotiating, and later developed the sense of conducting business; 'dealing' (the noun) arose from the verb with the -ing suffix, and 'dealings' is the plural form.

Initially, 'deal' meant 'to divide or distribute'. Over time its sense broadened to include 'to trade' or 'to conduct negotiations', and now 'dealings' commonly refers to transactions or interactions (business or personal).