A luau (in Hawaiian, lū‘au) is a traditional Hawaiian party or feast that is usually accompanied by entertainment. It may feature food such as poi, kalua pig, poke, lomi salmon, opihi, haupia, and beer; and entertainment, such as Hawaiian music and hula. Among people from Hawaii, the concepts of "luau" and "party" are often blended, resulting in graduation luaus, wedding luaus, and birthday luaus.

According to Pukui & Elbert (1986:214), the name "luau" goes back "at least to 1856, when so used by the Pacific Commercial Advertiser." Earlier, such a feast was called a pā‘ina or 'aha‘aina. The newer name comes from that of a food always served at a luau: young taro tops baked with coconut milk and chicken or octopus legs.

Luau-themed or Hawaiian-themed parties can be differentiated from authentic luaus by a lack of traditional food and techniques as described above. These parties range dramatically in their range of dedication to Hawaiian traditions. For example, some extravagant affairs go so far as to ship food from the islands, while others settle for artificial leis, maitais, and a poolside atmosphere. None of these are considered Luaus by purists.