Bible Dictionaries
Trefoil

The American Church Dictionary and Cyclopedia

An ornament used in Gothic architecture, formed by mouldings in the head of window lights, tracery, panelings, etc., so arranged as to resemble the trefoil, (i.e., three leaved) clover, as an emblem of the Trinity.

Bibliography Information
Miller, William James. Entry for 'Trefoil'. The American Church Dictionary and Cyclopedia. https://www.studylight.org/​dictionaries/​eng/​acd/​t/trefoil.html. 1901.