Are we there yet? Are we there yet? Are we there yet? When we pester someone, we annoy them with repeated questions or requests. And anyone who’s driven children on a long road trip might reasonably assume pester is related to pest. But au contraire. Etymology can be such a pest.
Pester, first recorded in the early 1500s, originally meant “to impede or entangle.” English got it from the French empestrer, which is believed to come from the Vulgar Latin *impastoriare, “to hobble an animal.” The base of impastoriare is the Medieval Latin pastoria, perhaps first used in the phrase pastoria chorda, “a rope (chorda) used to shackle an animal.” Pastoria, here, is a noun use of pastorius, “of a herdsman,” who had need for such equipment, else their livestock would stray. The base noun is pastor, “shepherd,” source of the same ministerial title and many other English words. Pastorious also supplies pastern, now the part of a horse’s foot where a shackle was once fixed.
English unshackled the em- in empestrer early on, probably because we just couldn’t resist the word’s likeness to pest, etymology be damned. By the 1560s, the record shows pester was being used for “infest” and “bother,” just like those lovable little backseat pests.