Nonresponder

Part of speech: noun

Definitions

1. A person or entity that fails to reply or react in a specific situation or to a particular stimulus
2. An individual who does not participate in a survey, study, or response task
3. Someone who does not provide feedback or engagement in communication or interaction

Etymology: "Nonresponder" is a plain compound: the prefix "non-" joined to "responder," and the second half is itself a borrowing. "Responder" comes from the Latin verb "respondere," meaning "to answer," which reached English by way of Old French "respondre" before the agent suffix "-er" was attached in English. The prefix "non-" is a Latin negating particle, so the whole word literally means "one who does not answer." The word is a modern formation built from familiar parts, most likely used in medical and psychological research, where it describes a subject who fails to show an expected reaction to a drug, treatment, or stimulus. Because the pieces are transparent, its history is short and its meaning follows directly from its parts. The useful detail is the contrast with "responder," which in the same clinical settings names someone who does respond, so the two words form a matched pair of opposites.