[ teer-ser-uh n ]
/ ˈtɪər sər ən /
(in a ribbed vault) a diagonal rib, other than an ogive, springing from a point of support.
Origin of tierceron
1835–45; < French, equivalent to tierce tierce + -eron noun suffix
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019