ret·i·na (r?t?n-?)n. pl. ret·i·nas or ret·i·nae (r?t?n-??) A delicate, multilayered, light-sensitive membrane lining the inner eyeball and connected by the optic nerve to the brain.[Middle English, from Medieval Latin r?tina, from Latin r?te, net.]ret?i·nal adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.retina (?r?t?n?) n, pl -nas or -nae (-?ni?) (Anatomy) the light-sensitive membrane forming the inner lining of the posterior wall of the eyeball, composed largely of a specialized terminal expansion of the optic nerve. Images focused here by the lens of the eye are transmitted to the brain as nerve impulses[C14: from Medieval Latin, perhaps from Latin r?te net] ?retinal adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ret?i?na (?r?t n ?, ?r?t n?) n., pl. ret?i?nas, ret?i?nae (?r?t n?i) the innermost coat of the posterior part of the eyeball that receives the image produced by the lens, is continuous with the optic nerve, and consists of several layers, one of which contains the rods and cones that are sensitive to light. [1350?1400; Middle English ret(h)ina