- inertia
- 1713, used as a term in physics 17c. by Ger. astronomer and physician Johann Kepler (1571-1630), from L. inertia "unskillfulness, idleness," from iners (gen. inertis) "unskilled, inactive," see inert. Used in Mod.L. by Newton (1687). Sense of "apathy" first recorded 1822.