In The Adventures of Huckleberry Finn, when Huck visits Mrs. Loftus disguised as a girl, what does he do that makes her discover his disguise?

 He forgets the name he gave himself as a girl.

Explanation:

He starts by saying Mary Williams, realizing his mistake he corrects himself to Sara Mary Williams.

true. the definition explains it: a word or phrase that modifies or qualifies an adjective, verb, or other adverb or a word group, expressing a relation of place, time, circumstance, manner, cause, degree, etc. this is a dictionary definition that i have looked up in a dictionary.