punctum

[pŭngktəm]
n. pl. punc•ta (-tə)
  1. The tip of a sharp anatomical process.
  2. A minute round spot differing in color or appearance from the surrounding tissues; a point.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Examples from the Web for punctum

Historical Examples of punctum