I am writing my thesis and I have decided to add a list of glossaries to explain certain terms. I decided to copy most definitions for these terms from here because I believe they are best explained there. This site, SEVOCAB provides definitions by the IEEE for international standards in Software and systems engineering.
1) Am I correct in copying directly the definitions from here? I thought it would be best to do so because you are using approved definitions to explain concepts that may frequently be interpreted differently by different authors
2) Of course I understand that I need to cite the website and that the definitions come from there. I thought of adding a sort of disclaimer or reference either at the beginning of the glossaries or somewhere in the thesis itself. For example, I have a section called clarification of terms whereby I make a distinction between Software Engineering and Software Development. How should I go about this?