unspottableadj.
Etymology: Previous versions of the OED give the stress as: unˈspottable.
the world > physical sensation > cleanness and dirtiness > [adjective] > unable to be dirtied
a1711 T. Ken Christophil in (1721) I. 516 Robes unspottable and bright.
This entry has not yet been fully updated (first published 1926; most recently modified version published online June 2019).