Mainly North American and Australian: as a boy's name this originated as a pet form of Randall, Randolf, or Andrew. As a girl's name it may have originated either as a transferred use of the boy's name or else as a pet form of Miranda (compare Randa). It is now fairly commonly used as an independent name, mainly by men, in spite of the unfortunate connotations of the colloquial adjective meaning ‘lustful’.
English (mainly East Anglia): habitational name from Lyng in Norfolk, so named from Old English hlinc ‘hillside’, or from either of two places in Norfolk and Lincolnshire named Ling, from Old Norse lyng ‘ling’, ‘heather’. There is also a Lyng in Somerset, so named from Old English lengen ‘long place’.