Testosterone

google

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1930s: from testis + sterone (blend of sterol and ketone).

wiktionary

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From test(is) +‎ -o- +‎ -sterone(“steroid hormone”).

etymonline

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testosterone (n.)

male sex hormone, 1935, from German Testosteron (1935), coined from a presumed combining form of Latin testis "testicle" (see testis) + first syllable of sterol + chemical ending -one.