Definition of "mag"

mag¹

/mæɡ/

noun
plural mags
1. (colloquial) Clipping of magazine.
2. (colloquial) Clipping of magnet.
3. (colloquial, automotive) Ellipsis of mag wheel.
4. (astronomy) Clipping of magnitude.
5. (colloquial, law) Clipping of magistrate.
6. (colloquial) Clipping of magnetometer.
  Quotations
  The policy is that all staff entering the Capitol are required to go through the mags whether or not they are with a Member of Congress.
  2010, United States. Congress. House. Committee on Appropriations. Subcommittee on Legislative Branch, Legislative Branch Appropriations for 2011: Hearings..., page 171
  “Take the f-ing mags away. Let my people in. They can march to the Capitol from here.”
  2022 June 28, Luke Broadwater, Michael S. Schmidt, quoting Donald Trump, “Trump Urged Armed Supporters to Capitol, White House Aide Testifies”, in The New York Times‎

mag²

/mæɡ/

verb
third-person singular simple present mags, present participle magging, simple past and past participle magged
1. (transitive, obsolete, slang) To steal.

mag³

/mæɡ/

noun
plural mags
1. (UK, slang, obsolete) A halfpenny.
  Quotations
  "Why, of course you wanted to get in," Mr. Bucket asserts with cheerfulness; "but for a old gentleman at your time of life […] not to consider that if he don't keep such a business as the present as close as possible it can't be worth a mag to him, is so curious! You see your temper got the better of you; that's where you lost ground," says Mr. Bucket in an argumentative and friendly way.
  1852 March – 1853 September, Charles Dickens, Bleak House, London: Bradbury and Evans, […], published 1853
  When all your tin is gone and spent, And you've not a mag for bread or rent
  1861, Philip William Perfitt, The Pathfinder, page 377