There are a lot of words ending in SSION including admission, commission, depression, expression, impression, mission, passion, recession, submission and transmission. However, there are no words beginning with the letter b and ending in SSION.
There are no words starting with the letter b and also containing the letters "ssion",
there are NO words in the English language that begin with "b" and end with "ssion" is there a chance you are misspelling your question?
bananabacteriabasilicaballerinabelugabandannabarracudabolognabulimia
Bewitch
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
ballast
bravery
backpack
baklava
buzzzz:)
being