hypaspist

from The Century Dictionary.

• noun In Greek antiquity, a shield-bearer or an armorbearer; an esquire; in the Macedonian army, one of a royal guard of light-armed foot-soldiers, so called from their shields.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Gr. Antiq.) A shield-bearer or armor-bearer.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a lightly-armoured military unit in Ancient Greece, who often served the purpose of distracting the foe from the frontline while holding an aspis and a spear, allowing the more mobile cavalry to strike the enemy from the flanks.