An Etymological Dictionary of Astronomy and Astrophysics

1. General: Something that remains after a process involving the removal of part of the original has been completed.
   

2. Math.: If f(z) is a → complex function, its residue at an isolated → singularity  z₀ is defined by the → integral (1/2πi) ∫f(z)dz taken along a simple closed curve interior to an annulus about z₀.

Etymology (EN): M.E., from O.Fr. residu, from L. residuum “a remainder,” neuter of residuus “remaining, left over,” from residere “to remain behind.”

Etymology (PE): Munak, from mun-, dialectal variant of mân-/mândan “to remain” (e.g., Farizani mundä, Gazi mun-, Khunsâri mûn-, Natanzi, Semnâni -mund, Yghnobi mun-), Mid.Pers. mân-/mândan “to remain, to stay;” O.Pers. mān “to remain, dwell;” Av. mān- “to remain, dwell;” cognate with E. → remain; + relation/diminution suffix -ak.