(an´u-lәs) pl. a´nuli Latin word meaning a small ring or encircling structure; also spelled annulus. anulus fibrosus fibrous ring of heart; any of four dense fibrous rings, one of which surrounds each of the major cardiac orifices. fibrous ring of intervertebral disk... Found on http://www.encyclo.co.uk/local/21001
anulus 1. A general anatomic nomenclature for a circular or ringlike structure; also written as annulus; however, some sources state that the spelling anulus is currently preferred. 2. In zoology, a ring-shaped structure; such as, any of the external segments of an annelid worm. Found on http://www.wordinfo.info/words/index/info/view_unit/137/