An Etymological Dictionary of Astronomy and Astrophysics

Similar or alike in every way; being the very same; agreeing exactly.

Etymology (EN): From M.L. identicus “the same,” from L.L. identitas “identity,” from idem “the same,” from id “it, that one” + demonstrative suffix -dem.

Etymology (PE): Yeksân “the same, similar,” from yek, → one, + -sân “manner, semblance” (variant sun, Mid.Pers. sân “manner, kind,” Sogdian šôné “career”).
Hamidân, from Mid.Pers. hamêtôn “identical.”