Thayer-69

αγρυπνεω, (ω; (αγρυπνος equiv. to αϋπνος); to be sleepless, keep awake, watch (equivalent to γρηγορεω); tropically, to be circumspect, attentive, ready: Mar_13:33; Luk_21:36; εις τι, to be intent upon a thing, Eph_6:18; υπερ τινος, to exercise constant vigilance over something (an image drawn from shepherds), Heb_13:17.

[SYNONYMS: αγρυπνειν, γρηγορειν, νηφειν: "αγρυπνειν may be taken to express simply ... absence of sleep, and, pointedly, the absence of it when due to nature, and thence a wakeful frame of mind as opposed to listlessness; while γρηγορειν (the offspring of εγρηγορα) represents a waking state as the effect of some arousing effort ... i.e. a more stirring image than the former. The group of synonyms is completed by νηφειν, which signifies a state untouched by any slumberous or beclouding influences, and thence, one that is guarded against advances of drowsiness or bewilderment. Thus it becomes a term for wariness against spiritual dangers and beguilements, 1Pe_5:8, etc." (Trench, Critical Notes on the N. T., note on Mar_13:33f).]