a rigid circular band of metal or wood or other material used for holding or fastening or hanging or pulling; "there was still a rusty iron hoop for tying a horse"
an imaginary line around the Earth forming the great circle that is equidistant from the north and south poles; "the equator is the boundary between the northern and southern hemispheres"
a circle dividing a sphere or other surface into two usually equal and symmetrical parts
the metabolic processes whereby certain organisms obtain energy from organic molecules; processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced and absorbed by the blood to be transported to the lungs
a single complete act of breathing in and out; "thirty respirations per minute"
respirator that produces alternations in air pressure in a chamber surrounding a patient's chest to force air into and out of the lungs thus providing artificial respiration