With identity terminology, no definition is absolute or applicable to 100% of people who use that term to describe themselves. We like to say that we embrace the 51/100 rule, meaning that if we can write a definition for a term that 51 out of 100 people who use that label personally would agree with, we’re nailing it. With this in mind, know that 49/100 people might disagree — slightly, or severely — with any definition your provide. That’s okay! Someone can use a word to mean something different from the definition here, and If you’re ever in doubt about a term that someone may prefer, ask the person!
These definitions and terms change (sometimes quite rapidly), so don’t be alarmed if you haven’t seen a term before or have heard a different definition.
PFLAG National Glossary
GLAAD Glossary of Terms: LGBTQ