reticulum

1. A netlike formation or structure; a network.
2. Zoology. The second compartment of the stomach of ruminant mammals, lined with a membrane having honeycombed ridges.
3. Reticulum A constellation in the Southern Hemisphere near Dorado and Horologium.

[Latin rēticulum, diminutive of rēte, net.]

1. A fine network formed by cells, by certain structures within cells, or by connective-tissue fibers between cells.
2. See neuroglia.
3. The second compartment of the stomach of ruminant mammals, lined with a membrane having honeycombed ridges.

Pl. reticula [L.]
1. a small network, especially a protoplasmic network in cells.
2. reticular tissue.
3. the smallest, most cranial section of the compound stomach of ruminants, lined with mucous membrane folded into a hexagonal pattern. Called also honeycomb. It communicates cranially with the esophagus and caudally with the rumen.

• r. (1) cell — see reticular1 cells.
• r. (1) cell leukemia — see malignant histiocytosis.
• r. (1) cell sarcoma — see cutaneous lymphosarcoma.
• endoplasmic r. (1) — an ultramicroscopic organelle of nearly all higher plant and animal cells, consisting of a system of membrane-bound cavities in the cytoplasm, occurring in two types: granular or rough-surfaced, bearing large numbers of ribosomes on its outer surface, and concerned mainly with protein production, and agranular or smooth-surfaced, concerned with lipid and glycogen synthesis and cholesterol metabolism. See also rough endoplasmic reticulum.
• sarcoplasmic r. (1) — a form of agranular reticulum in the sarcoplasm of striated muscle, comprising a system of smooth-surfaced tubules surrounding each myofibril.
• transmissible r. (1) cell tumor — see canine transmissible venereal tumor.
• transmissible venereal r. (1) cell tumor — see canine transmissible venereal tumor.

The noun has 2 meanings:

Meaning #1: any fine network (especially one in the body composed of cells or blood vessels)

Meaning #2: the second compartment of the stomach of a ruminant
  Synonym: second stomach