fine line(redirected from fine-line)
a fine line
A very narrow division between two deceptively similar things, one of which is worse than the other. As a new parent, you learn that there's a fine line between looking out for your child's welfare and being overprotective.
A narrow margin separating two things. A: "I only borrowed your sweater, I swear!" B: "Well, it's a fine line between borrowing and stealing, isn't it?"