Bewitch
Bellybuttons would be the longest word I can think of beginning with a 'b' and ending in an 's'.
ballast
being
blitz
Some seven letter words starting with B are:bathtubdisturbperturbproverbrhubarbsuccumbtaxicabwashtub
bananabacteriabasilicaballerinabelugabandannabarracudabolognabulimia
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
bias
ballast
ballast
buzzzz:)
being
bravery
backpack
baklava
blitz