The only one I can think if is mission. Check out your dictionary.
The word begging with ssion is bission
Some examples of words that end in "ssion" include expression, discussion, admission, and possession.
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
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
There are words that begin with letters a, c, d, e, f, i, m, n, o, p, r, s and t that end with the letters ssion. However, there are no words that begin with b and end with ssion.
admission compassion depression emission fission impression mission nonaggression obsession passion recession session transmission
abscissionadmissionaggressioncommissioncompassionconcessionconcussionconfessiondepressiondigressiondiscussiondispassionexpressionfissionimpressioningressionintermissionmissionoppressionobsessionpercussionpermissionpossessionprecessionprocessionprofessionregressionrepressionrescissionsessionsubmissionsuccessiontransmission
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