ametabolic

Ametabolic is an adjective used to describe the absence or notable reduction of metabolism. It is formed with the prefix a-, meaning without, combined with metabolic, which relates to metabolism—the set of chemical reactions that sustain life. The term is not standard in most biological or medical taxonomies and is encountered only sporadically in literature.

Because metabolism is a defining feature of living systems, ametabolic is rarely applied to describe real organisms. In practice, the word is more often used in theoretical, philosophical, or fictional contexts, or to describe specific conditions where metabolic activity is suppressed or not being measured, such as samples treated with inhibitors, or in discussions of near-zero metabolic states. In these uses, ametabolic can contrast with metabolic processes like glycolysis, energy production, or biosynthesis.

In formal writing, more precise terms are preferred, such as hypometabolic (reduced metabolism), dormant, anhydrobiotic (in dehydrated states), or sterilized/non-living contexts. If ametabolic is used, authors typically define what is being considered non-metabolic and the scope of "metabolic activity" being ignored. Because metabolism is a broad concept, the lack of standardized definition means ametabolic must be interpreted from context.

See also: metabolism, metabolic rate, dormancy, hypometabolism, anabolism, catabolism.