What is "acetabulum"

Acetabulum \Ac`e*tab"u*lum\, n. [L., a little saucer for vinegar, fr. acetum vinegar, fr. acere to be sour.]

1. (Rom. Antiq.) A vinegar cup; socket of the hip bone; a measure of about one eighth of a pint, etc.

2. (Anat.)

   1. The bony cup which receives the head of the thigh bone.

   2. The cavity in which the leg of an insect is inserted at its articulation with the body.

   3. A sucker of the sepia or cuttlefish and related animals.

   4. The large posterior sucker of the leeches.

   5. One of the lobes of the placenta in ruminating animals.

n. 1 (context Roman Antiquities English) a vinegar cup; 2 (context Roman Antiquities English) the socket of the hipbone; 3 (context Roman Antiquities English) a measure of about one eighth of a pint 4 (context anatomy English) The bony cup which receives the head of the thigh bone. 5 (context anatomy English) The cavity in which the leg of an insect is inserted at its articulation with the body. 6 (context anatomy English) A sucker of the sepia or cuttlefish and related animals. 7 (context anatomy English) The large posterior sucker of the leeches. 8 (context anatomy English) One of the lobes of the placenta in ruminating animals.

1. n. the cup-shaped hollow in the hipbone into which the head of the femur fits to form a ball-and-socket joint [syn: cotyloid cavity]

2. [also: acetabula (pl)]

The acetabulum (cotyloid cavity) is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.

In ancient dining, an acetabulum ( Greek: , , ) was a vinegar-cup, which, from the fondness of the Greeks and Romans for vinegar, was probably always placed on the table at meals to dip the food in before eating it. The vessel was wide and open above; and the name was also given to all cups resembling it in size and form, to whatever use they might be applied. The cups used by jugglers in their performances were also called by this name. They were commonly of earthenware, but sometimes of glass, silver, bronze, or gold. In anatomy, because of its shape, the acetabulum is the place of pelvis that meets with the head of the femur, forming the hip joint.

In Ancient Roman measurement, the acetabulum was a measure of volume (fluid and dry) equivalent to the Greek . It was one-fourth of the hemina and therefore one-eighth of the sextarius. It contained the weight in water of fifteen Attic drachmae.

Used with some frequency by Pliny the Elder, in a 1952 translation the unit was judged to be equivalent to 63 cubic centimeters. However, other sources estimate a higher value of perhaps 68 cc (see Ancient Roman units of measurement).

Acetabulum ( plural acetabula) in invertebrate zoology is a saucer-shaped organ of attachment in some annelid worms (like leech) and flatworms. It is a specialised sucker for parasitic adaptation in trematodes by which the worms are able to attach on the host. In annelids, it is basically a locomotory organ for attaching to a substratum. The name also applies to the suction appendage on the arms of cephalopod molluscs such as squid, octopus, cuttlefish, Nautilus, etc.