isosterism

[ ahy-sos-tuh-riz-uh m ]
/ aɪˈsɒs təˌrɪz əm /

noun

Chemistry. the quality or state of being isosteric.
Pharmacology. the theory that isosteric compounds have identical or similar pharmacological action.

Origin of isosterism

First recorded in 1860–65; isostere + -ism