(physics) Any of several electronic devices that control electron current through vacuum, gas or vapor between electrodes within a sealed container, usually of glass or metal and often designed to be easily installed in and removed from the equipment in which it is used.

(anatomy) In humans and other land vertebrates, a tube that links the nasopharynx to the cavity of the middle ear to allow the equalization of the pressure on both sides of the eardrum.

a photoelectric device for intensifying faint astronomical images

the tube that develops from the wall of a pollen grain and, in seed plants, provides a passage through which the male nuclei reach the embryo sac to effect fertilization

(anatomy) Either of the two ducts in female mammals through which ova pass from the ovaries to the uterus.

(chemistry) a glass tube, rounded at one end and open at the other; used for small-scale laboratory tests

produced in a test tube / conceived or developed in vitro by artificial insemination

Alternative letter-case form of venturi tube

A device in some early internal combustion engines that ignited the fuel/air mixture in a tube heated by a flame

A phototube in which an electric current flows when a certain illumination is reached; used as a relay