- a gelatinlike product of certain seaweeds, used for solidifying certain culture media, as a thickening agent for ice cream and other foods, as a substitute for gelatin, in adhesives, as an emulsifier, etc.
- a culture medium having an agar base.
- a complex gelatinous carbohydrate obtained from seaweeds, esp those of the genus Gelidium, used as a culture medium for bacteria, a laxative, in food such as ice cream as a thickening agent (E406), etc