self-interested

the compound 'self-interested' is a relatively modern formation, built upon the established english word 'self' and the noun 'interest', which entered english via old french from the latin phrase 'interest' meaning 'it makes a difference'. the latin root combines 'inter-' (between) and 'esse' (to be), conveying the idea of something that lies between parties, hence concerning them. by adding the adjectival suffix '-ed' to the noun phrase 'self interest', the word literally means 'having one's own concern or advantage at heart', evolving to describe a person primarily motivated by personal benefit, often with a connotation of disregarding others. this logical construction transparently reflects the shift from a neutral state of having an interest to the character trait of being focused on it.

Structure: self (own) + interest (benefit, attention) + ed (adjective suffix) self: from old english 'self', of germanic origin; a reflexive pronoun meaning 'own, same'. interest: from latin 'interest' ('it is of importance'), from 'inter-' (between) + 'esse' (to be); the noun form meaning advantage or attention. ed: from old english '-ed', '-od', '-ad', a suffix forming adjectives from nouns or verbs, indicating possession of a quality.