Hemoglobin

google

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mid 19th century: a contracted form of haematoglobulin, in the same sense.

wiktionary

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Originally hematinoglobulin, from hematin (from Ancient Greek αἷμα(haîma, “blood”) + -in) + -o- + globulin (from Latin globus(“ball, sphere”) + -in).

etymonline

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hemoglobin (n.)

also hæmoglobin, coloring matter in red blood cells, 1862, shortening of hæmatoglobin (1845), from Greek haimato-, combining form of haima (genitive haimatos) "blood" (see -emia) + globulin, a type of simple protein, from globule, formerly a word for "corpuscle of blood."