As is known, the term "Imam" can mean very different things, depending on the context. It can refer to the leader of a prayer, the selected leader of a masjid or religious community, or even just a general term of respect for particular Islamic scholars. And under Shi'ite Imamah, it also refers to the divinely appointed leader of the Islamic state. And questions that relate strongly to any one such interpretation have little to no actual overlap with the others.
According to the tag wiki for imam,
The Imam is the religious leader of the community/mosque.
This is clearly in line with the general Sunni sense of the term. However, the earliest questions which still use this tag are using it in the Shi'ite sense. And by cursory examination, its usage seems to be roughly split half and half between the Sunni and Shi'ite usage.
From the perspective of providing useful categorization of topics, this tag has clearly failed.
For the leader of the prayer, the existing imam-al-jamaah is probably sufficient. There are many cases where imam-khatib and imam-al-jamaah would refer to the same person, but imam-al-jamaah seems to be valuable on its own, and not unique to either Shi'ites or Sunnis.
For the Shi'ite-exclusive use of the term, either re-tagging it to imamah or creating a new shia-imam seem to be the most feasible options (I lack domain expertise to know how viable either of those actually are, or especially whether there would be a far better option, feedback is welcome).
However, this would not actually prevent the confusion of the existing imam; leaving the extant tag around will inevitably result in people just using it as they have been, based on their own understanding of what the term "Imam" entails. Even if synonyming it to any of the alternatives would prevent future users from misusing it, given how strongly and popularly the term maps to very different things it would be more trouble than its worth to decide (and enforce) which alternative actually "deserves" the synonym.
As such, I feel that removing the tag entirely is in the site's best interest. Every question tagged imam (current and future) needs to be actively re-tagged according to the actual usage of the term.
"Imam" is confusing. Please use a more precise tag based on what you actually mean:
- imam-khatib: The selected/appointed leader of the religious community/mosque
- imam-al-jamaah: The person who is leading a congregational prayer
- shia-imam: the divinely appointed successor to leadership of the Islamic state à la Shi'ite Imamah
Update: This has been completed. The three new tags have been created and wikied, and all existing questions (when relevant) have been re-tagged into one of the three. For all intents and purposes, the original imam should now be considered deprecated.