A line on a person's body where darker, tanned skin meets paler skin which is not tanned, typically because it has been covered by clothing during exposure to sunlight, sunlamps, etc.
Origin
1940s; earliest use found in Emporia (Kansas) Gazette. From tan + line.
Definition of tan line in US English:
tan line
nounˈtan lʌɪn
A line on a person's body where darker, tanned skin meets paler skin which is not tanned, typically because it has been covered by clothing during exposure to sunlight, sunlamps, etc.
Origin
1940s; earliest use found in Emporia (Kansas) Gazette. From tan + line.