Astigmatism in which different parts of the same meridian have different degrees of curvature.
What Are Irregular Verbs?Verbs (the action words in sentences) are grouped as either regular and irregular, based on whether they follow standard rules of conjugation. Some common irregular verbs include go, have, make, say, take, and know. Regular Verbs To form the past tense of a regular verb, just add -d or -ed to the end of it. For example, learn becomes learned in the past tense. Irregular …
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.