'fair-deal' is a compound of 'fair' and 'deal'. 'fair' originates from Old English 'fæger' where it meant 'beautiful, agreeable' and later took on senses of 'just' or 'impartial', and 'deal' originates from Old English 'dǣl' meaning 'part, portion' or 'a distribution/transaction'.

'fair' changed from Old English 'fæger' through Middle English 'fair' with senses of pleasing and then just; 'deal' came from Old English 'dǣl' to Middle English 'deel' meaning 'part, portion' or 'transaction'. The modern compound phrase 'fair deal' developed in Modern English as a description for an equitable agreement.

Initially the components related to pleasing portions or parts ('fair' as pleasing/beautiful, 'deal' as a portion), but over time the combined phrase evolved to mean 'an equitable or just agreement' in modern usage.