agar

noun

ˈä-gər 

1

: a gelatinous colloidal extract of a red alga (as of the genera Gelidium, Gracilaria, and Eucheuma) used especially in culture media or as a gelling and stabilizing agent in foods

2

: a culture medium containing agar

Examples of agar in a Sentence

Recent Examples on the Web

In lab tests, Petri dishes containing Penicillin-PPG-doped agar were inoculated with E. coli bacteria, then half of each dish was covered with a light-blocking aluminum sticker. —Ben Coxworth, New Atlas, 13 June 2025

Add tomato juice to a small sauce pan and bring to boil, add agar agar and reduce heat stirring constantly. —Claudia Alarcón, Forbes.com, 30 May 2025

There was some nutrient agar in the bottom, and a bunch of little, tiny plants. —Dr. Matthew Lisy, Hartford Courant, 1 Feb. 2025

The agar provides all the moisture and nutrients the growing plants need. —Dr. Matthew Lisy, Hartford Courant, 1 Feb. 2025

Word History

Etymology

short for Malay agar-agar, name for the red alga from which it is extracted

First Known Use

1885, in the meaning defined at sense 1

Phrases Containing agar

• agar-agar
• agar plate

Rhymes for agar

• gager
• jager
• sager
• vaguer

Kids Definition

agar

noun

ˈäg-ər 

variants also agar-agar

ˈäg-ə-ˈräg-ər

1

: a jellylike substance obtained from a red alga and used especially in culture media or to give firmness to foods

2

: a culture medium containing agar

Medical Definition

agar

noun

ˈäg-ər 

1

: a gelatinous colloidal extract of a red alga (as of the genera Gelidium, Gracilaria, and Eucheuma) used especially in culture media or as a gelling and stabilizing agent in foods

2

: a culture medium containing agar