An Etymological Dictionary of Astronomy and Astrophysics

1. No longer in effect or use; not operating or functioning.
   

2. No longer in existence; dead; extinct.

Etymology (EN): M.E., from O.Fr. defunct or directly from L defunctus “dead,” literally “off-duty,” from p.p. of defungi “to discharge, finish,” from → de- “off, completely” + fungi “perform or discharge duty,” from PIE root *bheug- “to enjoy” (cognates: Latin fructus).

Etymology (PE): Nâkâr, “disabled” (Dehxodâ), leterally “not working,” from negation prefix nâ-, → un-, + kâr, kardan,
→ work