S: (n) antrum (a natural cavity or hollow in a bone)
S: (n) cloaca ((zoology) the cavity (in birds, reptiles, amphibians, most fish, and monotremes but not mammals) at the end of the digestive tract into which the intestinal, genital, and urinary tracts open)
S: (n) vestibule (any of various bodily cavities leading to another cavity (as of the ear or vagina))
S: (n) mediastinum (the part of the thoracic cavity between the lungs that contains the heart and aorta and esophagus and trachea and thymus)
S: (n) pericardial cavity, pericardial space (the space between the layers of the pericardium that contains fluid that lubricates the membrane surfaces and allows easy heart movement)
S: (n) vacuole (a tiny cavity filled with fluid in the cytoplasm of a cell)
S: (n) ventricle (one of four connected cavities in the brain; is continuous with the central canal of the spinal cord and contains cerebrospinal fluid)
S: (n) sac (a structure resembling a bag in an animal)
S: (n) uterine cavity (the space inside the uterus between the cervical canal and the Fallopian tubes)
S: (n) nasal cavity (either of the two cavities lying between the floor of the cranium and the roof of the mouth and extending from the face to the pharynx)
S: (n) cecum, caecum, blind gut (the cavity in which the large intestine begins and into which the ileum opens) "the appendix is an offshoot of the cecum"
S: (n) chest cavity, thoracic cavity (the cavity in the vertebrate body enclosed by the ribs between the diaphragm and the neck and containing the lungs and heart)
S: (n) abdominal cavity, abdomen (the cavity containing the major viscera; in mammals it is separated from the thorax by the diaphragm)
S: (n) pelvis, renal pelvis (a structure shaped like a funnel in the outlet of the kidney into which urine is discharged before passing into the ureter)
S: (n) pelvic cavity (the space bounded by the bones of the pelvis and containing the pelvic viscera)
S: (n) celom, coelom, celoma (a cavity in the mesoderm of an embryo that gives rise in humans to the pleural cavity and pericardial cavity and peritoneal cavity)
S: (n) pit, fossa (a concavity in a surface (especially an anatomical depression))
S: (n) ear (the sense organ for hearing and equilibrium)
S: (n) kettle, kettledrum, tympanum, tympani, timpani (a large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it)