Definition of "ocellus" [‖O•cel•lus]

• A small simple eye, found in many invertebrates, usually consisting of a few sensory cells and a single lens. (noun)
• A marking that resembles an eye, as on the tail feathers of a male peacock; an eyespot. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In dinoflagellates, four types of eye-spots are known: type A, an independent structure that is not membrane-bound; type B, an independent membrane-bound structure; type C, structure as part of a chloroplast; and type D, an elaborate eye-like structure called ocellus"
• "All have compound eyes and may or may not have a single ocellus over each eye."
• "Aquila In nubibus Imperator literatorum, columen literarum, abyssus eruditionis, ocellus Europae, Scaliger."