Where do the references / sources for Definitions go in a thesis? I have been asked to historicise my terms, so i have a brief explanations for each definition in the front matter section. Where do the references for these go? With the references  with the main text? Or should I list the references in the front matter with the definitions? (It's a cultural history research study).  Thank you.
Ask your advisor. There may be conventions for your field.
One possibility: If they are references, tootnote them the way you do any other references in the body of the thesis. If they are brief explanations, consider an appendix.