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trachea

(Encyclopedia)trachea trāˈkēə [key] or windpipe, principal tube that carries air to and from the lungs. It is about 41⁄2 in. (11.4 cm) long and about 3⁄4 in. (1.9 cm) in diameter in the adult. It extends fr...

Eustachian tube

(Encyclopedia)Eustachian tube yo͞ostāˈshən [key] [for Bartolomeo Eustachi], a hollow structure of bone and cartilage extending from the middle ear to the rear of the throat, or pharynx, technically known as the...

psychrometer

(Encyclopedia)psychrometer sīkrŏmˈĭtər [key], one of many instruments used for measuring the water vapor content or relative humidity of the atmosphere. It consists of two identical thermometers—the wet-bulb...

holmium

(Encyclopedia)holmium hōlˈmēəm [key] [Lat.,=Stockholm], metallic chemical element; symbol Ho; at. no. 67; at. wt. 164.93032; m.p. about 1,474℃; b.p. about 2,425℃; sp. gr. 8.78 at 25℃; valence +3. Holmium ...

jet stream

(Encyclopedia)jet stream, narrow, swift currents or tubes of air found at heights ranging from 7 to 8 mi (11.3–12.9 km) above the surface of the earth. They are caused by great temperature differences between adj...

hay fever

(Encyclopedia)hay fever, seasonal allergy causing inflammation of the mucous membranes of the nose and eyes. It is characterized by itching about the eyes and nose, sneezing, a profuse watery nasal discharge, and t...

speedometer

(Encyclopedia)speedometer, instrument that indicates speed. A cable from an automotive speedometer is attached to the rear of the transmission of an automobile; the cable turns at a rate proportional to the speed o...

William, prince of Wales

(Encyclopedia)William, (William Arthur Philip Louis), 1982–, Prince of Wales of Great Britian, eldest son of King Charles III and Diana ...

aerogel

(Encyclopedia)aerogel, any of a group of extremely light and porous solid materials; the lightest is less than four times as dense as dry air. Aerogels are produced from certain gels (see colloid) by heating the ge...

lungs

(Encyclopedia)lungs, elastic organs used for breathing in vertebrate animals, excluding most fish, which use gills, and a few amphibian species that respire through the skin. The word is sometimes applied to the re...