Look at your BUTT (Dont take it offensively).Its like two pieces of flesh together marked by a boundary in between them ..Thats abut .
A+But : 'But' is used to (ad)join two sentence as in example : He is good guy, but not a good student.
ab+hut=> all huts generally will be side by side.
abhut-"abe" hut jada pas aane ki koshish mat kar
note that in ABUT, A is adjacent to B in the alphabet(there's boundary between them),also U is adjacent to T.