trackless

Of a place: not having tracks or paths; pathless, untrodden; also, having had all tracks removed.

a trackless desert    a trackless forest

Associates! Solitude in trackless deserts, / Where locusts, ants, and lizards poorly thrive,— / […] / Were to an honest heart endurable, / Rather than such associates.

Leaving no track or trace when moving; also, not following any track or path.

What was it that I loved so well about my childhood's home? / It was the wide and wave-lashed shore, the black rocks crowned with foam! / It was the sea-gull's flapping wing, all trackless in its flight, / Its screaming note, that welcomed on the fierce and stormy night!

Of a train, tram, etc.: not running on tracks.

a trackless trolley