Definition

Noun: * The fourth and final chamber of the stomach in a ruminant animal, where true gastric digestion with acid and enzymes occurs. It is functionally analogous to the simple stomach of monogastric animals (like humans).

Examples

• The abomasum is often referred to as the "true stomach" of a cow.
• In young calves, milk bypasses the rumen and goes directly to the abomasum for digestion.
• A veterinarian examined the cow for a possible displacement of the abomasum.

Advanced Usage

• "Abomasal" (adjective): Pertaining to the abomasum.
  • The vet diagnosed an abomasal ulcer.
• The abomasum is distinct from the first three chambers (the rumen, reticulum, and omasum), which are involved in microbial fermentation and storage.

Variants and Related Words

• Abomasal (adj.): Of or relating to the abomasum.
• Rumen: The first and largest stomach compartment.
• Reticulum: The second stomach compartment.
• Omasum: The third stomach compartment.

Synonyms

• True stomach
• Fourth stomach
• Rennet stomach (historically, as it was a source of rennet)

Notes on Meaning

This is a highly specialized biological term used almost exclusively in veterinary science, zoology, and agriculture when discussing the anatomy of ruminants such as cattle, sheep, goats, and deer.

Noun

1. the fourth compartment of the stomach of a ruminant; the one where digestion takes place