Language does not exist in a vacuum, but rather is subject to the specific historical, cultural, and political context in which it develops. Additionally, as groups of people come into contact with each other and discover shared traits and experiences—often aided by the increased globalization and relative anonymity made possible by the internet—new terms are coined, and existing terms are expanded to account for these newfound similarities and differences.
Because of this, language is constantly in flux, and one person's understanding of a particular word may differ from another person's understanding. If you do not understand the context in which a person is using a term, it is generally appropriate to ask. This is especially true concerning terms that may have a derogatory connotation.
For the reasons above, we do not purport to serve as a definitive, up-to-date resource regarding the many ways in which words—especially identity terms—change in meaning over time. That said, we understand that it may be helpful to have resources to glean a rough approximation of what an unfamiliar term might mean to a person. To that end, below are some glossaries curated by reputable organizations that may be helpful: