Currently, I am falling short on recommenders for my PhD applications in the United States. I don't want to ask the professors with whom I only took a few classes as I know those letters could be weak. I have done 3 research projects and all my supervisors have already submitted letters of recommendation.
My question is whether I can ask for a letter from a professor with whom I not only had some classes, but who also viewed my undergraduate honors dissertation? I presented my presentation to my supervisor and this professor. However, while explaining my relationship with her, what will she be called? Since, it was not my Ph.D. thesis, I can't call her a member of my dissertation committee.