Columbia Encyclopedia

Search results

458 results found

tunicate

(Encyclopedia)tunicate to͞oˈnəkĭt [key], marine animal of the phylum Chordata, which also includes the vertebrates. The adult form of most tunicates (also called urochordates) shows no resemblance to vertebrate...

Franco, Francisco

(Encyclopedia)Franco, Francisco fränthēsˈkō frängˈkō [key], 1892–1975, Spanish general and caudillo [leader]. He became a general at the age of 32 after commanding the Spanish Foreign Legion in Morocco. Du...

vitamin

(Encyclopedia)vitamin, group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either t...

hydrocarbon

(Encyclopedia)hydrocarbon hīˌdrōkärˈbən [key], any organic compound composed solely of the elements hydrogen and carbon. The hydrocarbons differ both in the total number of carbon and hydrogen atoms in their ...

halogen

(Encyclopedia)halogen hălˈəjĕn [key] [Gr.,=salt-bearing], any of the chemically active elements found in Group 17 of the periodic table; the name applies especially to fluorine (symbol F), chlorine (Cl), bromin...

plutonium

(Encyclopedia)plutonium plo͞otōˈnēəm [key], radioactive chemical element; symbol Pu; at. no. 94; mass no. of most stable isotope 244; m.p. 641℃; b.p. 3,232℃; sp. gr. 19.84 at 20℃; valence +3, +4, +5, or ...

carbon cycle

(Encyclopedia)CE5 Carbon cycle carbon cycle, in biology, the exchange of carbon between living organisms and the nonliving environment. Inorganic carbon dioxide in the atmosphere is converted by plants into sim...

respiration

(Encyclopedia)CE5 Respiratory system respiration, process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is tran...

lobster

(Encyclopedia)lobster, marine crustacean with five pairs of jointed legs, the first bearing large pincerlike claws of unequal size adapted to crushing the shells of its prey. The segmented body of the lobster consi...

Luzon

(Encyclopedia)Luzon lo͞ozŏnˈ [key], island (1990 pop. 30,797,458), 40,420 sq mi (104,688 sq km), largest, most populous, and most important of the Philippine Islands. As the major island, Luzon has played the ...