Lamb. (Baby Sheep.) Hope this helped.
stub.
bias
bean
Four letter words starting with B and ending with W are blew, blow, brow, and brew.
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
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Scarab.
cherrub
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Ballerina is one 9-letter word beginning with B and ending with A.
herb.