Is arimidex a form of chemotherapy?

Arimidex can't be classified as chemotherapy ... but it definitely is used to slow the growth of some cancers.

Arimidex (anastrozole) lowers estrogen levels in postmenopausal women, which may slow the growth of certain types of breast tumors that need estrogen to grow in the body.

Arimidex is used to treat breast cancer in postmenopausal women. It is often given to women whose cancer has progressed even after taking tamoxifen (Nolvadex, Soltamox).

https://www.drugclasses.com/arimidex.html