What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
1Informal. A person who moons or idles about.
2Slang. A person who exposes his or her buttocks.
Late 16th century (in an earlier sense). In sense 1 from moon + -er, after post-classical Latin lunarius, itself probably arising from a misreading of limarius. In sense 2 from moon + -er.