According to Dragon Ball Wikia:
Akira Toriyama actually tried a number of poses when he was alone in
order to decide the coolest pose for the Kamehameha. After much
contemplation, he could not decide on a name for his "Kame" attack, so
he asked his wife who came up with the name. She told Akira that it
would be easy to remember the name of the attack if he uses the name
of the cultural Hawaiian king named Kamehameha (lit. "the very lonely
one" or "the one set apart" in Hawaiian language). Also, Kamehameha
means "Turtle Destruction Wave" in Japanese.
So, despite the literal translation in Japanese "Turtle Destruction Wave", Kamehameha is also a name of a Hawaiian king:
Kamehameha I (Hawaiian pronunciation: [kəmehəˈmɛhə]; c. 1758 – May 8,
1819), also known as Kamehameha the Great, conquered the Hawaiian
Islands and formally established the Kingdom of Hawaiʻi in 1810. By
developing alliances with the major Pacific colonial powers,
Kamehameha preserved Hawaiʻi's independence under his rule. Kamehameha
is remembered for the Kānāwai Māmalahoe, the "Law of the Splintered
Paddle", which protects human rights of non-combatants in times of
battle. Kamehameha's full Hawaiian name is Kalani Paiʻea Wohi o
Kaleikini Kealiʻikui Kamehameha o ʻIolani i Kaiwikapu kauʻi Ka
Liholiho Kūnuiākea.