trisomy (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.

suffix indicating state, condition, or quality; also activity or the result of it (as in victory, history, etc.), via Anglo-French and Old French -é, from Latin -ia, Greek -ia, from PIE *-a-, suffix forming abstract or collective nouns. It is etymologically identical with -ia and the second element in -cy, -ery, -logy, etc.