Retina

Part of speech: noun

Pronunciation: /ˈɹɛt.ɪ.nə/

Definitions

1. The inner layer at the back of the eyeball is essential for vision, converting light into electrical impulses that the brain interprets as images
2. This delicate tissue layer lines the posterior of the eye, playing a vital role in absorbing light and relaying visual signals to the brain
3. A thin, light-sensitive membrane located at the back of the eye that captures visual information and transmits it to the brain through the optic nerve

Etymology: The lining at the back of the eye that catches light was named for a net, and the name began as a description of blood vessels. The Greek physician Galen, writing in the 2nd century, used the phrase "amphiblēstroeidēs chitōn," meaning something like "net-like tunic," for this layer. The Latin version, "tunica retina," was later shortened to "retina," with "tunica" dropped, leaving the adjective to stand alone as a noun. The Latin phrase is attested in the 12th century in the writings of Guillelmus the abbot and Gerard of Cremona. Gerard may have created it as a translation of an Arabic phrase, "ṭabaqa shabakiyya," meaning "net-like layer," which itself rendered Galen's Greek. The word reached English in Middle English as "rethina," borrowed from the Medieval Latin.

Synonyms: nervous membrane, eye layer, photoreceptive layer, retinal layer, photoreceptor