Common words:
* Admission
* Commission
* Decision
* Discussion
* Expression
* Impression
* Mission
* Possession
* Profession
* Session
* Submission
* Transmission
Less common words:
* Accession
* Ascension
* Coalescence
* Concession
* Confession
* Dissension
* Eruption
* Erosion
* Excursion
* Fusion
* Intercession
* Obsession
* Precession
* Regression
* Repression
* Seizure
* Submersion
* Succession
* Suppression
* Transgression
Words ending in "ssion" from specific fields:
* Biogenesis (biology)
* Photoemission (physics)
* Translocation (biology)
This is not an exhaustive list, but it provides a good starting point for exploring words ending with "ssion."