bepester 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).

1520s, "to clog, entangle, encumber" (a sense now obsolete), probably a shortening of empester, impester, from French empestrer "place in an embarrassing situation" (Modern French empêtrer, Walloon epasturer), from Vulgar Latin *impastoriare "to hobble" (an animal), from Latin im- "in" + Medieval Latin pastoria (chorda) "(rope) to hobble an animal," from Latin pastoria, fem. of pastorius "of a herdsman," from pastor "herdsman" (see pastor (n.)).

Or directly from the French word. The sense of "annoy, disturb, trouble" (1560s) is from influence of pest. Related: Pestered; pestering.