Etymology: The origin of this is involved: 1. Old English had a transitive verb warian ‘to guard, take care or charge of,’ with a compound bewarian ‘to defend.’ The latter is not certainly found in Middle English (where it would have been bewaren ); the former survived as ware v.¹, common till 1500 with a dative reflexive construction, especially in the imperative ware thee! ‘cave tibi, take care of thyself, be on your guard, beware!’; and has been retained down to the present day in the simple imperative ware! , as ‘Ware holes!’ (although in this form it has often since 1600 been mistaken for a contraction of beware! or an interjectional use of the adjective). 2. Old English had also an adjective wær ‘cautus, cautious, on one's guard,’ which survived in Middle English as war , ware , common in the phrase to be ware ‘to be on one's guard,’ of which the imperative be ware! was practically = ware thee! aforesaid. 3. From this equivalence of meaning, be ware early began to be treated in some respects as a single word, viz. as a compound of the verb ware , thus stepping into the place of the Old English bewarian . As early as 1300 we find it written as one word, and even with by as the prefix, and in 14–15th cent. it often followed the verbal constructions of the simple ware , even to taking a direct object, as in ‘beware that train’ (a1600 at sense 1e). But on the other hand it was used only in those parts of the verb where be is found, viz. the imperative, infinitive, and present subjunctive (the indicative being I am ware , thou art ware , etc.). After 1600, the verbal aspect so far prevailed that the inflections bewares , bewared , bewaring , were used by good writers; but these have again been discarded, and beware is now used only where be ware would be a possible construction, viz. in the imperative (chiefly), the infinitive, and present subjunctive (rarely). The full evidence of these statements will be found under ware v.¹ and ware adj.: the following quotations show the relations of to be ware, to ware oneself, ware thee, ware to thee, be ware to thee, beware thee, beware thyself, before 1500.c1200 Trin. Coll. Hom. 5 [He] muneȝed us alle to ben warre þarof.1377 W. Langland Piers Plowman B. v. 452 Ware þe fram wanhope wolde þe bitraye.a1400 (a1325) Cursor Mundi (Vesp.) l. 62 He þat [s]titthest wenis at stand, Warre hym his fall is nexst his hand.a1425 (c1395) Bible (Wycliffite, L.V.) (Royal) (1850) Ecclus. xiii. 16 Be war [v.r. war] to thee, and take heede..to thin heryng.1470–85 T. Malory Morte d'Arthur (1816) II. 399 Be you beware also what ye do.1477 Earl Rivers tr. Dictes or Sayengis Philosophhres (Caxton) (1877) lf. 11^v Ware the of the wordes of lyers.1483 Vulgaria abs Terencio (T. Rood & T. Hunte) sig. nij Ware thy hede thy handys or fete.1484 W. Caxton tr. G. de la Tour-Landry Bk. Knight of Tower (1971) lxxvii. 108 A woman ought to beware her self.

Etymology: First c1400; < be- prefix 2 + ware v.² to spend (still in every-day use in the north).