The word 'unselfishness' is a modern English formation built by applying productive affixes to a core concept. Its foundation is the Old English noun 'self', meaning "one's own person," which has ancient Proto-Indo-European roots. The adjective 'selfish' emerged in the 17th century by adding the suffix '-ish' (having the character of) to 'self'. To negate this quality, the Old English prefix 'un-' (meaning "not") is attached, creating the adjective 'unselfish'. Finally, the abstract noun is formed by appending the Old English suffix '-nes', which concretizes the condition or quality of being unselfish. Thus, the word's logic is a clear, layered construction: the state (ness) of not (un) having the character of being concerned solely with oneself (selfish).

Structure: un (not) + selfish (selfish) + ness (state or quality) - un: A prefix of Germanic origin, meaning "not," used to give a word a negative or opposite force. - selfish: An adjective of English origin, derived from 'self' + '-ish', meaning "caring only about oneself." - ness: A noun-forming suffix of Germanic origin, used to form abstract nouns indicating a state, condition, or quality.