From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( n.) Persons added to a jury, commonly from those in or about the courthouse, to make up any deficiency in the number of jurors regularly summoned, being like, or such as, the latter.

(2): ( syntactically sing.) The writ by which such persons are summoned.

King James Dictionary [2]

Ta'Les, n. L. talis, plu. tales. In law, tales de circumstantibus, spectators in court, from whom the sheriff is to select men to supply any defect of jurors who are impaneled, but who may not appear, or may be challenged.