Noun
an imaginary straight line along which an observer looks
Source: WordNetline-of-sight
Hence, as the line of sight to the upper part is the longer, it makes that part look as if it were leaning back. But when the members are inclined to the front, as described above, they will seem the beholder to be plumb and perpendicular. Vitruvius
Never let a beautiful woman pick your path for you when there is a man in her line of sight. -Adie, Wizard's First Rule. Terry Goodkind
To photograph: it is to put on the same line of sight the head, the eye and the heart. Henri Cartier-Bresson
Forgive my parental panic. I tend to get a little nervous when you're not in my immediate line of sight these days." "Oh yeah? How long do you think that's going on for?" "Not long. Five, maybe six years." "Luke!" "I plan to let you start dating when you're thirty, if that helps. Cassandra Clare
One more night, God I've had to fight To keep my line of sight on what's real One more day I fear I've lost my way I don't know how to say what I feel. Tom Petty
4D spacetime If we extend this to three spatial dimensions, the null geodesics are the 4-dimensional cone: : so : This null dual-cone represents the "line of sight" of a point in space. Source: Internet