Noun, pl. foveolas or foveolae or foveolæ
(Anatomy)
1. The center of the fovea in the macula of the eye, approximately 0.35 mm in diameter, containing only cone cells. (wiktionary.org)
2. A yellowish, cone photo receptor filled portion of the human retina located within a region called the macula. The foveola is approximately 0.35 mm in diameter and lies in the center of the fovea and contains only cone cells, and a cone-shaped zone of Müller cells. (wikipedia.org)
Word origin: Latin word meaning a little pit (diminutive of Latin fovea).