ACL

noun

ˌā-(ˌ)sē-ˈel 

plural ACLs

: a cruciate ligament of each knee that attaches the front of the tibia with the back of the femur and functions especially to prevent hyperextension of the knee and is subject to injury especially by tearing

The athlete tore their ACL during a practice game.

called also anterior cruciate ligament

Examples of ACL in a Sentence

Recent Examples on the Web

Rashee Rice, who last year returned from his own ACL surgery, told me the adrenaline of an NFL game takes on a different speed. — Sam McDowell, Kansas City Star, 17 Sep. 2026

With Stribling, Pearsall and defensive lineman Mykel Williams (ACL) out, the 49ers are working without their top draft picks from the last three drafts. — Chris Biderman, Sacbee.com, 16 Sep. 2026

Cloé Lacasse, forward, Utah Royals Lacasse is playing her first full season for Utah after rupturing an ACL and spraining an MCL in 2024 and missing much of 2025. — Karan Lodha, New York Times, 16 Sep. 2026

Everyone tuned in to see Patrick Mahomes make his return nine months after tearing his ACL and LCL last December. — Alejandro Avila Outkick, FOXNews.com, 15 Sep. 2026

Word History

First Known Use

1981, in the meaning defined above

Medical Definition

ACL

noun

ˌā-(ˌ)sē-ˈel 

: anterior cruciate ligament