STI

noun

ˌes-ˌtē-ˈī How to pronounce STI (audio)
plural STIs
: any of various diseases or infections (such as gonorrhea, genital herpes, chlamydia, hepatitis B, or HIV) that are typically transmitted by direct sexual contact but may sometimes be spread by nonsexual means (such as childbirth or sharing needles)

called also STD

Examples of STI in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The lawsuit, filed in federal court in Maryland, centers around Title X, which Minnesota Attorney General Keith Ellison's office says helps low-income Americans get birth control, cancer screenings, STI testing, and other basic health care. — Wcco Staff, CBS News, 27 Aug. 2026 These exploits require some due diligence — especially with STI rates on the rise among people 55 and up. — Helen Carefoot, Flow Space, 21 Aug. 2026 Sometimes, the differences are fairly obvious; the wing on an STI versus a normal Subaru WRX comes to mind. — Caleb Jacobs, The Drive, 22 July 2026 Rainbow Community Center presents an afternoon of pride, visibility, celebration and resilience with live performances, DJs, community vendors and resources, a kids’ area, food and free HIV/STI testing. — Kate Bradshaw, Mercury News, 30 May 2026 See All Example Sentences for STI

Word History

Etymology

sexually transmitted infection

First Known Use

1983, in the meaning defined above

Time Traveler
The first known use of STI was in 1983

Browse Nearby Words

sthn
STI
stib
See all Nearby Words

Cite this Entry

“STI.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/STI. Accessed 1 Sep. 2026.

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Medical Definition

STI

abbreviation or noun
ˌes-(ˌ)tē-ˈī How to pronounce STI (audio)
: any of various diseases or infections (such as gonorrhea, genital herpes, chlamydia, hepatitis B, or HIV) that are typically transmitted by direct sexual contact but may sometimes be spread by nonsexual means (such as childbirth or sharing needles)

called also STD

Last Updated: - Updated example sentences
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