"study of flags," 1959, from Latin vexillum "flag, military ensign, banner" (from velum "a sail, curtain, veil; see veil (n.)) + -ology.
Entries linking to vexillology
veil n.
c. 1200, "nun's head covering," from Anglo-French and Old North French veil (12c., Modern French voile) "a head-covering," also "a sail, a curtain," from Latin vela, plural of velum "sail, curtain, covering," from PIE root *weg- (1) "to weave a web." Vela was mistaken in Vulgar Latin for a feminine singular noun. To take the veil "become a nun" is attested from early 14c.
-ology
word-forming element indicating "branch of knowledge, science," now the usual form of -logy. Originally used c. 1800 in nonce formations (commonsensology, etc.), it gained legitimacy by influence of the proper formation in geology, mythology, etc., where the -o- is a stem vowel in the previous element.
The second element is prop[erly] -logy (-logue, etc.), the -o- belonging to the preceding element; but the accent makes the apparent element in E[nglish] to be -ology, which is hence often used as an independent word. [Century Dictionary]