Madder

wiktionary

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From Middle English mader, madere, mædere, from Old English mædere, mæddre, mædre, from Proto-Germanic *madarǭ (compare Swedish madra, Old Norse / Icelandic maðra), from Proto-Indo-European *modʰro-, cognate with Proto-Slavic *modrъ(“blue”), and compare Irish madar(“madder”), Latvian madara(“madder”).

Inflected forms.

From Irish meadar.

etymonline

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madder (n.)

type of plant (in modern use Rubia tinctorum) yielding a valuable dyestuff, Old English mædere and Old Norse maðra, from PIE *modhro- "dye plant" (source also of Old High German matara "madder," Polish modry, Czech modry "blue").