An Etymological Dictionary of Astronomy and Astrophysics

1. Capable of being seen by, or perceptible to, the human eye.
   

2. → visible light.

Etymology (EN): M.E., from O.Fr. visible, from L. visibilis “that may be seen,” from visus, p.p. of videre “to see;” cognate with Pers.
bin, present stem of didan “to see”
(Mid.Pers. wyn-; O.Pers. vain- “to see;” Av. vaēn- “to see;”
cf. Skt. veda “I know;” Gk. oida “I know,” idein “to see;” PIE base *weid- “to know, to see”).

Etymology (PE): Diyâr “visible” in several dialects, e.g. štiyâni, Malâyeri, Širâzi, Tabari, related to didan “to see;” Mid.Pers. ditan “to see, regard, catch sight of, contemplate, experience;” O.Pers. dī- “to see;” Av. dā(y)- “to see,” didāti “sees;” cf. Skt. dhī- “to perceive, think, ponder; thought, reflection, meditation,” dādhye; Gk. dedorka “have seen.”
Padidâr (→ phenomenon) and peydâ are both also related to dā(y)-
(with prefixes).