petri dish

noun

pe·​tri dish ˈpē-trē- 

variants or less commonly Petri dish

plural petri dishes also Petri dishes

1

: a small shallow usually round dish of thin glass or plastic with a loose cover used especially for growing cells or microorganisms on a supportive medium (such as agar combined with nutrients)

… the protein extracted from human cancer cells could stimulate the growth of blood vessels in experiments with chicken embryos and tumor cells growing in petri dishes.

—Tina Hesman

Unfortunately, most laboratories can diagnose tuberculosis with certainty, or exclude it, only by placing sputum in a petri dish and waiting to see if the bacterium grows …

—The New York Times

… they found that the compound, sulforaphane, fights cancer in petri dishes.

—Doug Levy

2

: something (such as a place or situation) that fosters development

Of course being there for your team tends to contaminate your team. Our radio studio is currently a petri dish of disease.

—Matt Heath

"We view universities as a community's most promising petri dish for innovation," said Abby Taubner …

—Alex Wittenberg

MTV's The Real World, which sends seven attractive young strangers to spend six months turning their luxury housing into a Petri dish of sexual, racial, and interpersonal tension, has been running since 1992.

—Francine Prose

Examples of petri dish in a Sentence

Recent Examples on the Web

And only months later did this wide-scale immigration enforcement campaign begin … on the streets of LA as sort of the petri dish, the guinea pig for expanding this across the country. —Tonya Mosley, NPR, 5 Jan. 2026

Or based on some microbes in a petri dish or a study of worms. —CBS News, 3 Jan. 2026

The longer a follicle sits in a petri dish, the lower its survival rate. —Daniel Fusch, USA Today, 2 Jan. 2026

Compounds manufactured for the petri dish are not held to the same strict standards as those made for human use. —Sarah Zhang, The Atlantic, 23 Dec. 2025

Word History

Etymology

Julius R. Petri †1921 German bacteriologist

First Known Use

1892, in the meaning defined at sense 1

Rhymes for petri dish

• cuttlefish
• jellyfish
• sablefish
• bluefish
• catfish
• codfish
• crawfish
• dogfish
• finfish
• flatfish
• goldfish
• groundfish

Kids Definition

Petri dish

noun

Pe·​tri dish

ˌpē-trē-

: a small shallow dish of thin glass or plastic with a loose cover used especially for cultures of bacteria

Medical Definition

petri dish

noun

pe·​tri dish

variants also Petri dish

ˈpē-trē- 

: a small shallow usually round dish of thin glass or plastic with a loose cover used especially for growing cells on a supportive medium (such as agar combined with nutrients)