tercio (iou)

tercio noun. . In sense 1 also tertio. L16.

A regiment of Spanish (or, formerly, Italian) infantry, orig. of the 16th and 17th cents. Also gen., a body of infantry forming a main division of an army. L16.
a. Bullfighting. Each of the three stages of a bullfight. Also called suerte. M20.
b. Each of the three concentric circular areas into which a bullring is considered to be divided. M20.