STI

noun

ˌes-ˌtē-ˈī

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.

Despite these advancements, STI rates in the United States continue to rise. — Care Resource, Miami Herald, 6 Apr. 2026 Epstein also said that Gates had wanted to try to give that STI medication to French Gates in secret. — Ava Berger, NPR, 8 Apr. 2026 Unfortunately, each year Congress suggests cutting funding to both STI and healthcare access programs. — Casey Pinto, The Conversation, 1 May 2026 Research has linked it not just to vaginal symptoms, but also to fertility, pregnancy outcomes, STI risk, gynecologic cancers and more. — Helen Carefoot, Flow Space, 28 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

See more words from the same year

Browse Nearby Words

sthn

STI

stib

See all Nearby Words

Cite this Entry

Style

“STI.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/STI. Accessed 7 Jul. 2026.

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Medical Definition

STI

abbreviation or noun

ˌes-(ˌ)tē-ˈī

called also STD

STI

noun

Examples of STI in a Sentence

Word History

Browse Nearby Words

Cite this Entry

Medical Definition

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