besiege (v.)

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).

early 13c., segge, "a seat, chair, stool; ceremonial seat of a king," senses now obsolete, from Old French siege, sege "seat, throne," from Vulgar Latin *sedicum "seat," from Latin sedere "to sit" (from PIE root *sed- (1) "to sit").

The military sense, "the stationing of an attacking force before or around a fortified place; the act or process of besieging a city, castle, etc." is attested from c. 1300; the notion is of an army "sitting down" before a place.

The oldest sense preserved in archaic Siege Perilous (early 13c.), the vacant seat at Arthur's Round Table, according to prophecy to be occupied safely only by the knight destined to find the Grail. Also in Middle English "a privy, a latrine, chamber pot" (c. 1400), hence in 16c. "excrement, fecal matter; the anus."