These are astrophysics notes to myself to assist me in comprehending astrophysics research lectures and papers. They might help you do the same.
The terms and concepts here vary from the basic and/or trivial to highly specialized and obscure, some only in current research, and some likely used only within one paper. It is also scattershot rather than organized or complete: it's things I looked up while attempting to understand a lecture or paper.
Caveat: I am not an astrophysicist and I make mistakes and harbor misconceptions, so if you are depending upon what you are learning, take these explanations as no more than a hint.