sad [OE] The original meaning of sad in Old English was ‘having no more appetite, weary’. The word comes from the same root as Latin satis ‘enough’, the source of satiated, satisfactory, and satisfy (all LME), and the idea was similar to our expression fed up [E20th]—of being unhappy through being too ‘full’ of something. The word then developed through ‘firm, constant’ and ‘dignified, sober’ to our modern sense of ‘unhappy’ in the medieval period.