oxytocin

noun

oxy·​to·​cin ˌäk-si-ˈtō-sᵊn 

: a pituitary octapeptide hormone C₄₃H₆₆N₁₂O₁₂S₂ that stimulates especially the contraction of uterine muscle and the secretion of milk

Examples of oxytocin in a Sentence

Recent Examples on the Web

After your baby is born progesterone (which inhibits breastmilk production) drops and prolactin, which controls milk volume, and oxytocin, which triggers the let-down reflex increases, explains Nadine Rosenblum, the perinatal lactation program coordinator at The Johns Hopkins Hospital. —Hannah Silverman, Parents, 16 Feb. 2026

The extra pressure also may signal the brain to release what’s called the love hormone, also known as oxytocin. —Adithi Ramakrishnan, Los Angeles Times, 10 Feb. 2026

Another key hormone is oxytocin, which plays a role in stress regulation. —Katia Hetter, CNN Money, 21 Dec. 2025

Just as a woman’s oxytocin levels increase with their child, a Japanese study found that owners experienced a 300 percent increase in oxytocin after spending 30 minutes with their dog. —Alyce Collins, MSNBC Newsweek, 30 Nov. 2025

Word History

Etymology

oxytoc(ic) + -in entry 1

Note: According to Science News Letter, vol. 12, no. 341 (October 22, 1927), p. 259, the name was given after pituitary extracts were "obtained in purified form from a single gland by Dr. Oliver Kamm and associates working in the research laboratories of Parke Davis and Company at Detroit."

First Known Use

1928, in the meaning defined above

Rhymes for oxytocin

• bosun
• formosan
• mnemosyne
• streptozotocin

Medical Definition

oxytocin

noun

oxy·​to·​cin -ˈtōs-ᵊn 

1

: an octapeptide hormone C₄₃H₆₆N₁₂O₁₂S₂ secreted by the posterior lobe of the pituitary gland that stimulates especially the contraction of uterine muscle and the secretion of milk

called also alpha-hypophamine

2

: a synthetic version of oxytocin used especially to initiate or increase uterine contractions (as in the induction of labor) see pitocin