noun. A substance used in a chemical reaction to detect, measure, examine, or produce other substances.

noun. In experimental psychology: The observer in any form of psychological experiment: opposed to experimenter.

noun. Same as reactor.

noun. One who or that which exerts reflex action or influence; an agency that produces reciprocal effects; a cause or source of counter-results.

noun. In chem., a substance used to effect chemical change in another substance for the purpose of identifying its component parts or of ascertaining its percentage composition.

noun. Anything used for the treatment of a substance under investigation to render its nature or condition more evident.

noun. A substance capable of producing with another a reaction, especially when employed to detect the presence of other bodies; a test.

noun. A usually available or readily made compound or known mixture of compounds used to treat materials, samples, other compounds or reactants in a laboratory or sometimes an industrial setting.

noun. a chemical agent for use in chemical reactions

"The most remarkable feature of Tebbe's reagent is a methylene group bridging between titanium and aluminum, which could replace the oxygen in a carbonyl group in a Wittig-like reaction."