n.
Pronunciation: k ə - ' ta-l ə -s ə s
Function: noun
Inflected Form: plural -y · ses \ - ˌ s ē z \
Etymology: Greek katalysis dissolution, from katalyein to dissolve, from kata- + lyein to dissolve, release ― more at LOSE
Date: 1836
: a modification and especially increase in the rate of a chemical reaction induced by material unchanged chemically at the end of the reaction