Vexillology is the scholarly study of flags. The word is a synthesis of the Latin word vexillum, meaning "flag", and the suffix -logy, meaning "study of". The vexillum was a particular type of flag used by Roman legions during the classical era; its name is a diminutive form of the word vela meaning sail, and thus literally means "little sail". Unlike most modern flags, which are suspended from a pole or mast along a vertical side, the square vexillum was suspended from a horizontal crossbar along its top side, which was attached to a spear.
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