Radiomimetic: Imitating radiation.
A radiomimetic drug is one that imitates the effects of radiation as in the case of chemicals such as nitrogen mustards which are used in cancer chemotherapy.
The "mimetic" part of "radiomimetic" comes from the Greek verb "mimeisthai" meaning "to imitate" and from "mimos" meaning "mime." (The English word "mime" also comes from "mimos" as do "mimic" and "mimicry.")