Emily Dickinson Lexicon

LAB'A-RUM, n. [origin unknown.]

The standard borne before the Roman emperors. It was a long pike, having a transverse beam, to which was attached a silken veil, wrought with images of the monarch and his children, and on the top was a crown of gold inclosing the mysterious monogram representing the cross, with the initial letters the name of Christ. The word is sometimes used for any other standard or flag. – See Ainsworth's Dict. and Gibbon's Hist. ch. xx.