The story
From [Term?] + (mac)rol(ide) + -imus (“immunosuppressant”).
Etymology from Wiktionary, CC BY-SA 4.0.
sirolimus
Today it means: An immunosuppressive drug C₅₁H₇₉NO₁₃ that is a macrocyclic lactone obtained from a soil bacterium Streptomyces hygroscopicus and is taken orally especially to prevent rejection of transplanted organs. Full definition →