Wiktionary
n. the division between skin that has darkened or tanned from exposure to sun and skin that has not been exposed to sun
Wikipedia
The Tân line (; chi can also be translated to as branch) was the sixteenth dynasty of Hùng kings of the Hồng Bàng period of Văn Lang (now Viet Nam). Starting approximately 660 B.C., the line refers to the rule of Đức Quân Lang and his successors.
Usage examples of "tan line".
She had a round belly and the trace of a Florida tan line below the navel.
She danced her fingertips over her tan line, which to Nate looked more like a beige line.
He looked at his father in his baggy swimming trunks, the dark tan line ending on the upper arms, the slight pot belly, the pale chest beginning to curve in at the center as age approached.
Margo dissolved into giggles as we passed another billboard, this one showing a puppy pulling at the bottom of a little girl's bathing suit, showing off her splendid tan line.
Her eyes settled on the tan line, a sexy rim of lighter skin beneath his navel.
It was printed in red pencil on old tan line paper like I used to use in grade school with Mrs.
Although she wasn't vain she hated a tan line-better to be the same brown all over.