on the look-out , on the watch; watching for any thing (post-Aug.): Festus Hadrumeto, ubi speculabundus substiterat, etc., Tac.H. 4, 50: ab ostio speculabunda, Mart. Cap. 2, § 112.—With acc.: speculabundus ex altissimā rupe identidem signa, Suet.Tib. 65.