The Origin and Evolution of Corollary

Corollary comes from the Late Latin noun corollarium, which can be translated as "a garland given as a reward." "Corollarium" comes from the Latin corolla, meaning "small crown or garland." If you know that a garland or small crown was sometimes given to actors in addition to their pay, it makes sense that another sense of "corollarium" is "gratuity." Later, "corollarium" developed the philosophical sense of a supplementary proposition that follows directly from one that has been proved. (You can think of a corollary as a "bonus" that follows from the proof of something else.) The broader modern sense, "something that naturally follows," evolved from the philosophical one.