any remains, impression, or trace of a living thing of a former geologic age, as a skeleton, footprint, etc.

a markedly outdated or old-fashioned person or thing.

a linguistic form that is archaic except in certain restricted contexts, as nonce in for the nonce, or that follows a rule or pattern that is no longer productive, as the sentence So be it.

of the nature of a fossil

fossil insects.

belonging to a past epoch or discarded system; antiquated

a fossil approach to economics.

noun

deposit , eolith , impression , neolith , paleolith , petrifaction , reconstruction , relic , skeleton , specimen , trace , fogy , fuddy-duddy , mossback , ammonite , antiquated , antique , conodont , coprolite , ichnite