bivy bag

noun

variants or bivy sac or less commonly bivvy bag or bivvy sac

: a collapsible bag made of weatherproof fabric that is used to provide shelter usually for a single person in the wilderness

All night the rain came in wind-lashed waves that hammered at the nylon bivy bag …

—Craig Medred, Anchorage Daily News, 30 Sept. 1990

I was comfortably warm in my sleeping bag and bivvy bag …

—Clive Tully, Geographical Magazine, March 1990

I crawled back to my bike and unhooked my survival kit—a bivy sack, sleeping bag and foam pad.

—Jill Homer, Juneau (Alaska) Empire, 16 Mar. 2008

This well-designed, compact bivvy sack is easy to slide into and protects best when temperatures are above 9C.

—Toronto Star, 16 Aug. 2008

Word History

First Known Use

1975, in the meaning defined above

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!