isopiptesis

English

Alternative forms

• isepiptesis

Etymology

Refashioning of the earlier spelling isepiptesis, from German Isepiptesen used by Alexander von Middendorff in his 1855 work Die Isepiptesen Russlands, from iso- + Ancient Greek ἐπίπτησις (epíptēsis, “flying down upon”), from ἐπι- (epi-, “upon”) + πτῆσῐς (ptêsis, “flight”), from πέτομαι (pétomai, “fly”).

Noun

isopiptesis (plural isopipteses)

1. An isoline that joins points on a map where the individuals of a particular migratory species arrive at the same time each year.
   • 1892, J. A. Palmén, “Report on the Migration of Birds”, in C. W. Shoemaker, transl., Annual Report of the Smithsonian Institution‎^[1]:

     The conclusion that the migration takes place at right angles to the isopipteses seemed justified; but, with regard to the direction of the bird's migration to be ascertained, could not possibly prove more exact than the premises themselves, the methods of inquiry, and the material.