inertial

the word 'inertial' is built upon its root 'inert', which entered english in the 17th century from latin 'iners, inert-', meaning 'unskilled, inactive'. this latin term itself is a compound of the negative prefix 'in-' and 'ars' (genitive 'artis'), signifying 'art' or 'skill'. thus, the original sense was literally 'without skill' or 'idle'. the scientific concept of 'inertia', the property of matter by which it continues in its existing state of rest or uniform motion, was coined by galileo and later defined by newton, abstracting the idea of inactivity or resistance to change in motion from the earlier human characteristic. the adjective 'inertial' directly pertains to this physical property, completing the journey from a description of human idleness to a precise term in physics.

Structure: in (not) + ert (skill, art) + ial (adjective suffix) in- (latin, negative prefix), ert (latin, from 'ars/artis' meaning skill, art), -ial (latin, adjective-forming suffix meaning 'pertaining to').