'well-mixed' originates from the combination of 'well' and 'mixed', where 'well' is an adverb meaning 'in a good or satisfactory way' and 'mixed' is the past participle of 'mix', meaning 'to combine or blend into one mass'.

'well-mixed' changed from the Old English word 'gemengan' (to mix) and eventually became the modern English word 'mix', combined with 'well' to form 'well-mixed'.

Initially, 'mix' meant 'to combine or blend', and this meaning has largely remained the same in modern usage.