absorb
adverb
aplomb
cherub
cobweb
entomb
scarab
suburb
superb
hubbub; entomb; bicarb
Bellybuttons would be the longest word I can think of beginning with a 'b' and ending in an 's'.
Eight letter words beginning with b, ending with e:backsidebaselinebegrudgebelittleblockadeblockagebreakage
thumb
Scarab.
cherrub
thumb
Ballerina is one 9-letter word beginning with B and ending with A.
djebel
Some seven letter words starting with B are:bathtubdisturbperturbproverbrhubarbsuccumbtaxicabwashtub
Caleb fdhrsb
carob climb