Chromosome

wiktionary

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19th century: from German Chromosom, ultimately from Ancient Greek χρῶμα(khrôma, “colour”) + σῶμα(sôma, “body”) (because they are stained under the microscope). Equivalent to chromo- +‎ -some.

etymonline

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chromosome (n.)

1889, from German Chromosom, coined 1888 by German anatomist Wilhelm von Waldeyer-Hartz (1836-1921), from Latinized form of Greek khrōma "color" (see chroma) + -some (3)). So called because the structures contain a substance that stains readily with basic dyes.