longboard

A longboard is a surfboard that is more than about 9 feet long (about
2.75 metres). Because they were originally designed in Malibu Beach
California, they are often called a malibu board, except at Malibu Beach where they are not called that. A traditional longboard has
one large fin underneath. Newer styles have three fins in a
thruster configuration, similar to many shortboards.

Can also refer to skateboards over 32 inches in length. These are mainly used for carving, cruising, hill bombing, or just plain transportation, but not often for tricks.

Generally have larger diameter wheels than their smaller counterparts, most commonly 65mm - 75mm, but some people like to add big ass, monster truck looking rubber wheels to go off road. Also usually equipped with wider trucks designed for high speeds.
Longboards come in wood and fiberglass variations. Some quality longboard manufacturers:

• www.flexdecks.com
• www.sector9.com
• www.road-rash.com
• www.bare-back.com

Also, a windsurfing board which is longer than 320 centimetres and having a volume of not less than 200 litres. Longboards have a daggerboard besides a fin, which other windsurfing boards don't. The main functional distinction between longboards and shortboards is that longboards are meant to be used in a non-planing (displacing) mode.

Longboards are mostly used for learning to windsurf and for relaxed cruising in the sun. It's possible to learn to ride a longboard in 1-3 hours, given appropriate conditions and a good teacher.