Of Hawaiian and Frisian/Germanic origin.

In Hawaiian Kai means sea.

In Hawaii it is used as a masculine and feminine name.

Kai is also used in the Netherlands, Sweden, Germany, Denmark and Finland.

Origin in these countries is considered Germanic, Frisian and it is used as a diminutive for the names Nicolaas and Gerhard.

Alternative forms of the European name Kai are Kay, Cai, Caj, Kaj.

Famous bearers are Kai Wiesinger, Kai Winding, Kai Lennox, Kai James, Kai Roeffen, Kai Owen, Kai Schumann.

Actress Jennifer Connelly named her first son Kai.