vexillum

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Botany See standard.
2. n. Zoology The weblike part of a feather; the vane.

Century Dictionary and Cyclopedia

1. n. In Roman antiquity: Strictly, the standard of a maniple; hence, any military standard, whatever its character, except the eagle of the legion.
2. n. The troops collected under a vexillum; a company; a troop; any body of soldiers serving under an ensign separate from that of the legion; hence, under the empire, the body of veteran soldiers connected with a legion who, having served sixteen years in the legion, were detached under a vexillum of their own, with special privileges, for their remaining four years of service. These vexilla averaged from 500 to 600 in strength.
3. n. Eccles.: A processional banner; also, a processional cross.
4. n. A kind of flag or pennon attached by a cord to the upper part of a bishop's pastoral Staff. It is folded round the staff, to prevent the metal of which the staff is made, or with which it is mounted, from being tarnished by the moisture of the hand. Also orarium, sudarium, veil.
5. n. In heraldry, same as banderole, .
6. n. In botany, the standard, or large posterior petal, of a papilionaceous flower. It is external, and wrapped around the others in the bud. Also vexil. See cut under papilionaceous.
7. n. In ornithology, a pogonium. web, or vane of a feather; also, both webs together with the rachis upon which they are borne. Also called standard.

Wiktionary

1. n. A flag, banner, or standard.
2. n. A company of troops serving under one standard.
3. n. The sign of the cross.
4. n. botany The upper petal of a papilionaceous flower.
5. n. zoology The rhachis and web of a feather taken together; the vane.

GNU Webster's 1913

1. n. A flag or standard.
2. n. A company of troops serving under one standard.
3. n. A banner.
4. n. The sign of the cross.
5. n. (Bot.) The upper petal of a papilionaceous flower; the standard.
6. n. (Zoöl.) The rhachis and web of a feather taken together; the vane.