biohazard

noun

bio·​haz·​ard ˈbī-ō-ˌha-zərd How to pronounce biohazard (audio)
: a biological agent or condition that is a hazard to humans or the environment
also : a hazard posed by such an agent or condition
biohazardous
ˌbī-ō-ˈha-zər-dəs How to pronounce biohazard (audio)
adjective

Examples of biohazard in a Sentence

The gasoline spill created a serious biohazard.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Items that are blood-stained can’t be returned as that’s considered a biohazard. — Howard Cohen, Miami Herald, 19 Mar. 2026 My visit to the pig facility felt like touring a biohazard site. — Burkhard Bilger, New Yorker, 29 June 2026 The potential biohazard posed by millions of pounds of spoiling food is a concern, Kleinman said. — Hayley Smith, Los Angeles Times, 21 June 2026 Researchers still need permits to collect and handle dead animals from the road because of potential biohazard and traffic risks. — Devika Rao, TheWeek, 3 Feb. 2026 See All Example Sentences for biohazard

Word History

First Known Use

1965, in the meaning defined above

Time Traveler
The first known use of biohazard was in 1965

Rhymes for biohazard

See All Rhymes for biohazard

Browse Nearby Words

biohacking
biohazard
bioherm
See all Nearby Words

Cite this Entry

“Biohazard.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/biohazard. Accessed 7 Jul. 2026.

Copy Citation

Medical Definition

biohazard

noun
bio·​haz·​ard ˈbī-ō-ˌhaz-ərd, -ˈhaz- How to pronounce biohazard (audio)
: a biological agent or condition (as an infectious organism or insecure laboratory procedures) that constitutes a hazard to humans or the environment
also : a hazard posed by such an agent or condition
biohazardous
-ˈhaz-ərd-əs How to pronounce biohazard (audio)
adjective
Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)
See More

Popular in Wordplay

See More

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

Is that lie 'bald-faced' or 'bold-faced'?

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
hangman letters and game
Hangman Lightning Round Figure out which word fits in the blanks.
See All