Columbia Encyclopedia

Search results

167 results found

ray, in zoology

(Encyclopedia)ray, extremely flat-bodied cartilaginous marine fish, related to the shark. The pectoral fins of most rays are developed into broad, flat, winglike appendages, attached all along the sides of the head...

skin cancer

(Encyclopedia)skin cancer, malignant tumor of the skin. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Rarer forms include mycosis fungoides (a type of lymphom...

learning

(Encyclopedia)learning, in psychology, the process by which a relatively lasting change in potential behavior occurs as a result of practice or experience. Learning is distinguished from behavioral changes arising ...

leprosy

(Encyclopedia)leprosy or Hansen's disease hănˈsənz [key], chronic, mildly infectious malady capable of producing, when untreated, various deformities and disfigurements. It is caused by the rod-shaped bacterium ...

neurosis

(Encyclopedia)neurosis, in psychiatry, a broad category of psychological disturbance, encompassing various mild forms of mental disorder. Until fairly recently, the term neurosis was broadly employed in contrast wi...

nursing

(Encyclopedia)nursing, science of providing continuous care for sick or infirm people. While nursing as an occupation has always existed, it is only in fairly recent years that it has developed as a specialized pro...

birth

(Encyclopedia)birth or labor, delivery of the fetus by the viviparous mammal. Birth is also known as parturition. Human birth normally occurs about 280 days after onset of the last menstrual period before conceptio...

diabetes

(Encyclopedia)diabetes or diabetes mellitus məlīˈtəs [key], chronic disorder of glucose (sugar) metabolism caused by inadequate production or use of insulin, a hormone produced in specialized cells (beta cells ...

Freud, Sigmund

(Encyclopedia)Freud, Sigmund froid [key], 1856–1939, Austrian psychiatrist, founder of psychoanalysis. Born in Moravia, he lived most of his life in Vienna, receiving his medical degree from the Univ. of Vienna i...

X ray

(Encyclopedia)CE5 Typical X-ray composite spectrum (intensity as a function of frequency) X ray, invisible, highly penetrating electromagnetic radiation of much shorter wavelength (higher frequency) than visibl...