Meaning and name origin
Rien \rien\ as a boy's name is of Latin and Gaelic origin, and the meaning of Rien is "of the sea; king". Rien is a variant of Marino (Latin); Marinus was the name of two saints: a third-century Roman martyr, and a legendary saint for whom the Italian republic of San Marino is named. Also a variant of Ryan (Gaelic): also possibly (Gaelic) "water".
Rien is not a popular first name for males and an equally uncommon surname or last name for all people (2000 U.S. Census).