Definition of "modal auxiliary" []

• A verb characteristically used with other verbs to express mood or tense. In English, the modal auxiliaries are can, may, must, ought, shall, should, will, and would. Also called modal. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In “I may bollix up this explanation,” may is the modal auxiliary that sets the conditional mode, sometimes called “subjunctive mood,” of the verb bollix, a verb whose ancient nautical coinage has its genesis in genitals."