[1920–25; thyro- + -trophic]This word is first recorded in the period 1920–25. Other words that entered Englishat around the same time include: Unknown Soldier, follow-up, fundamentalism, montage, zipperthyro- is a combining form representing thyroid in the formation of compound words. Other words that use the affix thyro- include: thyrotome, thyrotomy, thyrotoxic, thyrotoxicosis, thyrotropin