Definition of "plus fours" []

• Loose knickers bagging below the knees, worn formerly for sports. (noun-plural)

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.

• "Stenning heaved himself up out of the rear cockpit and jumped down; he was in plus fours and a flying helmet."
• "We secured a table on the shady patioa great place, really, a place of peace; you could imagine Scotsmen in caps and plus fours sitting there a hundred years earlier."