The phrase "faint line" typically means a very light or not very clear line. It can refer to things like a thin mark on paper or a faint mark on a pregnancy test that shows an uncertain result.
Sentences with «faint line»
I really like the way you added faint lines of blue. (athomeonthebay.com)
Draw faint lines with a pencil to create the shape you need. (craftstylish.com)
Draw in faint lines along the edge of your lip. (health.com)