'embitter' originates from Middle English, specifically the word 'embittren,' where 'em-' meant 'to make' and 'bitter' meant 'having a sharp taste or feeling.'

'embittren' transformed into the modern English word 'embitter' through Middle English.

Initially, it meant 'to make bitter,' and over time it evolved into its current meaning of 'to cause someone to feel bitter or resentful.'