vexillarii
Could not find vexillariorum in Logeion dictionaries.
vexillariorum Noun: masculine genitive plural of vexillarii
VEXILLARII
VEXILLA´RII[EXERCITUSVol. 1. p. 792.]
Vexillarii
The oldest class of Roman veterans, who, at the end of their period of service, retired from the legion, but were kept together under a standard (vexillum) up to the time of their final dismissal. They formed, by the side of the legion, a select corps like the evocati of earlier times. They were exempt from ordinary service, and only bound to take part in actual fighting. See evocati.