(anatomy) In higher vertebrates, a large air-filled space above and behind the nose in the middle of the face.

(anatomy) The large vein which returns blood from the head, neck, thorax and both upper limbs to the right atrium of the heart.

(anatomy) The large vein which returns blood from the lower extremities, and the pelvic and abdominal organs, to the right atrium of the heart.

(anatomy) Either of the two large veins that take oxygen depleted blood, from the upper body and from the lower body, and return it to the right atrium of the heart.

(collective) A procession of riders, vehicles, ships, etc. / A ceremonial parade. / A trail ride, usually more than one day long. / (by extension) An often dramatic series or chain of events or things.

To move as part of a series or group, such as marchers in a parade or snow in an avalanche, especially in large numbers or in a chaotic or dangerous fashion

The act of something collapsing or caving in. / The location where something has caved in. / (idiomatic) The act of relenting.

To collapse inward or downward. / (figuratively) To relent; to grant approval against one's initial will.

The formation of pits on a surface. / (fluid dynamics) The formation, in a fluid, of vapor bubbles that rapidly collapse, especially in a rotating marine propeller or pump impeller.

(originally intransitive, of horses) To prance, frolic, gambol. / (intransitive) To move about carelessly, playfully or boisterously.