The only one I can think if is mission. Check out your dictionary.
Words ending in ssion: mission profession passion permission session admission discussion
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.
Gnatssion
fission - a nuclear reaction
i only now one and that is ........ MISSION
Mission, fission, session, secession, succession, discussion, percussion, permission, precession, and procession all end with 'ssion'.
There are no words starting with the letter b and also containing the letters "ssion",
Expression
abscissionadmissionaggressioncommissioncompassionconcessionconcussionconfessiondepressiondigressiondiscussiondispassionexpressionfissionimpressioningressionintermissionmissionoppressionobsessionpercussionpermissionpossessionprecessionprocessionprofessionregressionrepressionrescissionsessionsubmissionsuccessiontransmission
admission compassion depression emission fission impression mission nonaggression obsession passion recession session transmission
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?
Admission Aggression