U18 or U-18 may refer to:
*; Geometry
**
Small rhombihexahedron
*; Military
**
German submarine U-18
''U-18'' may refer to one of the following German submarines:
* , was a Type U 17 submarine launched in 1912 and that served in the First World War until sunk on 23 November 1914
** During the First World War, Germany also had these submarines w ...
, a disambiguation page
**
U-18, a Soviet World War II experimental self-propelled gun.
An under-18 youth sport teams or competition, including:
*;Association football:
**
:Under-18 association football, one of many under-18 association football (soccer) teams
*;Basketball:
**
USA Women's U18 and U19 teams
The USA women's national under-19 basketball team is the women's basketball team, administered by USA Basketball, that represents the United States in international under-19 and under-18 (under age 19 and under age 18) women's basketball competiti ...
, two of the teams under the auspices of the USA Basketball organization
*;Ice hockey:
**
IIHF World U18 Championship, an annual event organized by the International Ice Hockey Federation for national under-18 ice hockey
** the
Ivan Hlinka Memorial Tournament
The Hlinka Gretzky Cup is an annual international under-18 ice hockey tournament administered by Hockey Canada, the Czech Ice Hockey Association, and the Slovak Ice Hockey Federation.
Held since 1991, it has been contested under various titles ...
, also known as the U-18 Junior World Cup, an annual event for national under-18 ice hockey teams from around the world
*;Volleyball:
**
Girl's Africa Volleyball Championship U18, a sport competition for women's national under-18 volleyball teams, held by theConfédération Africaine de Volleyball, the Africa volleyball federation
**
NORCECA Girls Youth Continental Championship U-18
The NORCECA Girls Youth Continental Championship U-18 is a sport, sport competition for national volleyball teams, currently held biannually and organized by the North, Central America and Caribbean Volleyball Confederation, NORCECA, the North Amer ...
, a sport competition for women's national under-18 volleyball teams, held by the North America, Central America and Caribbean volleyball federation
**
South America Volleyball Championship U18, a sport competition for national under-18 volleyball teams, held by the Confederación Sudamericana de Voleibol, the South America volleyball federation.
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