(physics) a dark or bright line in an otherwise continuous spectrum caused by the absorption or emission of light, at a single wavelength, by the movement of electrons between energy levels of an atom or molecule

(geometry) A line that, meeting or tending to meet another, makes oblique angles with it.

(geography) A line on a map through points of equal elevation, often height above sea level.

the division between skin that has darkened or tanned from exposure to sun and skin that has not been exposed to sun

A long elastic cord tied around the ankles of the jumper in bungee jumping.

The final part of a joke; the word, sentence, or exchange of sentences that is intended to be funny and provokes laughter from the listeners.

A path that pedestrians or vehicles take informally rather than taking a sidewalk or set route, for example, a well-worn ribbon of dirt cutting across a patch of grass, or a path in the snow.

A type of commercial fishing using a very long line with many baited hooks attached along its length.

(fine arts) An abstract line supposed to be beautiful in itself and absolutely; differently represented by different authors, often as a kind of elongated S (like the one drawn by Hogarth).

(military, weaponry) direction in which a weapon fires / (figuratively, by extension) position vulnerable to attack