An Etymological Dictionary of Astronomy and Astrophysics

A device with a restricted aperture, located in an optical system at any of several points, that cuts off marginal light rays not essential to image formation.

Etymology (EN): From L.L. diaphragma, from Gk. diaphragma “partition, barrier,” from diaphrassein “to barricade,” from dia-
“across” + phrassein “to fence or hedge in.”

Etymology (PE): Miyânban, from miyân “middle, interior, between” (Mid.Pers. miyân “middle,” Av. maiδya-, maiδyāna- “medium, middle,” cf. Skt. mádhya- “middle, intemediate,” Gk. mesos “middle,” L. medius “middle,” Goth. midjis, O.E. midd “middle,” O.C.S. medzu “between,” Arm. mej “middle,” PIE *medhyo- “middle,” , from base *me- “between”) + band “barrier, shutter,” from
bastan “to bind, shut” (Mid.Pers. bastan/vastan “to bind, shut,” Av./O.Pers. band- “to bind, fetter,” banda- “band, tie,” cf.
Skt. bandh- “to bind, tie, fasten,” PIE *bhendh- “to bind”).