The increase in rate of a chemical reaction caused by the presence of a catalyst. / An amount of catalyst, expressed as the increase of the rate of its reaction.

plural of Ya

(chiefly Canada, US) The coypu, Myocastor coypus. / The fur of the coypu.

(pharmacology) An anticholinergic drug used in the bromide form, in combination with vilanterol, for the treatment of chronic obstructive pulmonary disease.