A phenomenon produced by an agent identical with or immunologically related to an agent that has altered the capacity of a certain tissue to react.
When To Use Definite vs. Indefinite ArticlesArticles are a unique type of adjectives that indicate which noun (person, place, or thing) you’re talking about. The only definite article in English is the, and it refers to a specific noun. Indefinite articles (a or an) refer to nouns more generally. Indefinite Articles Indefinite articles refer to non-specific nouns. Think “I need a pen” or “I want an orange.” In both cases, we …
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.