noun
heraldry
The academic study of coats of arms and heraldic traditions.
彼は大学で紋章学を専攻している。
He is majoring in heraldry at university.
紋章 refers to a coat of arms or crest itself, while 紋章学 is the study of such symbols.
Compound of 紋章 (coat of arms) and 学 (study, -ology).