non-responder

The word is a modern English compound built from established morphemes. The core, "respond," originates from the Latin respondēre, itself from re- (back) and spondēre (to pledge, promise), conveying the idea of a pledged answer. The negative prefix "non," directly from Latin, negates the action. The agent suffix "-er," of Germanic origin, is then appended to form a noun denoting an entity that does not provide the expected answer or reaction. Thus, the term's logic is transparent: it literally describes "one who does not answer back," which in specialized contexts like medicine or research refers to a subject showing no reaction to a given stimulus or therapy.

Structure: non (not) + respond (answer) + er (person/thing that does) - non: A prefix of Latin origin meaning "not." - respond: A verb from Latin respondēre, meaning "to answer, promise in return." - er: An agent noun suffix of Old English origin, indicating "a person or thing that performs the action."