word-forming element of verbs and nouns from verbs, with a wide range of meaning: "about, around; thoroughly, completely; to make, cause, seem; to provide with; at, on, to, for;" from Old English be- "about, around, on all sides" (the unstressed form of bi "by;" see by (prep.)). The form has remained by- in stressed positions and in some more modern formations (bylaw, bygones, bystander).
The Old English prefix also was used to make transitive verbs and as a privative prefix (as in behead). The sense "on all sides, all about" naturally grew to include intensive uses (as in bespatter "spatter about," therefore "spatter very much," besprinkle, etc.). Be- also can be causative, or have just about any sense required. The prefix was productive 16c.-17c. in forming useful words, many of which have not survived, such as bethwack "to thrash soundly" (1550s) and betongue "to assail in speech, to scold" (1630s).
c. 1300, "to put, place (somewhere)," verbal use of Old English noun stow "a place, spot, site, locality" (common in place names), from Proto-Germanic *stowo- (source also of Old Frisian sto "place," Middle Low German, Middle Dutch stouwen, Dutch stuwen "to stow," Old High German stouwen "to stop, check," German stauen "to stow, pack; bring to a halt, hem in"), from PIE *stau- "stout, standing, strong," extended form of root *sta- "to stand, make or be firm" (source also of Old Church Slavonic stavljo "to place," Lithuanian stoviu, stovėti "to stand"). The nautical sense of "put away to be stored, pack" (1550s) was enforced by Dutch stouwen "to cram, pack up close." Related: Stowed; stowing.