bunt (v.)

"hit with the head, strike by thrusting" (as with the end of a beam or thick stick), c. 1200, from Anglo-French buter, Old French boter "push, shove, knock; thrust against," from Frankish or another Germanic source (compare Old Norse bauta, Low German boten "to strike, beat"), from Proto-Germanic *butan, from PIE root *bhau- "to strike."

The meaning "join at the end, be contiguous" is from 1660s, partly a shortening of abut. To butt in "rudely intrude" is American English slang, attested from 1900. Related: Butted; butting.

"to leap, spring upward, jump," 1590s, from French bondir "to rebound, resound, echo," from Old French bondir "to leap, jump, rebound;" originally "make a noise, sound (a horn), beat (a drum)," 13c., ultimately "to echo back," from Vulgar Latin *bombitire "to buzz, hum" (see bomb (n.)), perhaps on model of Old French tentir, from Vulgar Latin *tinnitire.