Douglas Harper's Etymology Dictionary
"study of flags," 1959, from Latin vexillum "flag, military ensign, banner" (from velum "a sail, curtain, veil; see veil (n.)) + -ology.
Wiktionary
n. The study of flags
Wikipedia
Vexillology is the scientific study of the history, symbolism and usage of flags or, by extension, any interest in flags in general. The word is a synthesis of the Latin word vexillum ("flag") and the Greek suffix -logia ("study.") The constitution of the International Federation of Vexillological Associations (known by its French acronym, FIAV) formally defines vexillology as "the creation and development of a body of knowledge about flags of all types, their forms and functions, and of scientific theories and principles based on that knowledge."
A person who studies flags is a vexillologist; vexillography is the art of designing flags; one who does so is a vexillographer; an admirer of flags is a vexillophile.
Vexillology is the second studio album by Canadian progressive house music producer deadmau5 released on November 6, 2006 by Play Digital. The album marks a change of style from that of his previous breakbeat and IDM oriented album Get Scraped for the progressive house genre. The album title comes from the term for the study of flags and their symbols.