immarˈcesciblyadv. [compare post-classical Latin immarcescibiliter (7th cent. or earlier)] rare unfadingly, enduringly.
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a1656 Bp. J. HallInvisible World (1659) iii. xii. 220 A crown..immarcescibly eternall, a crown of righteousnesse.
1902 O. Seaman in T. A. Cook Anthol. Humorous Verse 140 Ruffling her caudal plumes derisive of scuts; Inconscient how she stalks an immarcessibly absurd Bird.