'dick' originates from English, specifically the nickname 'Dick', where 'Dick' was a diminutive of the name 'Richard' (from Old French and Germanic roots).

'dick' changed from the pet form 'Dick' of the medieval name 'Richard' and was used as a generic familiar name for a man; later, from colloquial use as a name for a man, it developed slang senses including 'penis' and 'unpleasant person'.

Initially, it meant 'a familiar form of the name Richard', but over time it evolved into slang senses such as 'a man' and specifically 'penis' and 'an insulting term for a person'.