Is this defamation of character and if so...plz help?

Okay heres the deal, I've been working at my company for many years. Now lately certain coworkers and close friends of mine have been telling me that the supervisor of their department has been making very petty remarks about me. Such as she says everytime she walks by my cubicle she says all I'm doing is looking in the mirror or spaced out on the computer. She also calls me "the other one" instead of my name. She even slipped up and said it to my face. Other things she has said is how can I buy a house when I'm a single woman and she has also said I'm actually out relaxing rather than doing my job ( which sometimes means going to other offices). On top of that she says she has no idea what I do and she even told someone she was thinking of going to a higher up to tell them this. I am a great worker, I dont know what is wrong with this woman. Is this considered slander? How can I prove it considering ive heard it from others? Also, should I confront her?