I've noticed a couple of synonyms regarding Raspbian versions that would benefit from being synonyms:
jessie (441 questions) and raspbian-jessie (4 questions)
stretch (76 questions) and raspbian-stretch (40 questions)
There is also a wheezy tag but no raspbian-wheezy. As for which tags should be the master tag and which the synonym: I personally think [raspbian-*] would work better, and would make it slightly easier if [raspbian] was ever to be split into version tags. However, it appears that the other tags (just the version names alone) are more popular with question askers.
We also have the semi-redundant tags raspbian-lite and jessie-lite, although it's not clear whether they should be synonymsied as raspbian-lite could also have questions about Stretch Lite.
Can (and indeed should) these tags be synonyms?