(mathematics) a set of entries in a square matrix running diagonally either from the upper left to lower right entry or running from the upper right to lower left entry
an oblique line of squares of the same color on a checkerboard; "the bishop moves on the diagonals"
a line or cut across a fabric that is not at right angles to a side of the fabric
(geometry) a straight line connecting any two vertices of a polygon that are not adjacent
at an angle; especially connecting two nonadjacent corners of a plane figure or any two corners of a solid that are not in the same face; "a diagonal line across the page"
one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism or a layer of sedimentary rock)
line thrown from a vessel that people can cling to in order to save themselves from drowning
line that raises or lowers a deep-sea diver
support that enables people to survive or to continue doing something (often by providing an essential connection); "the airlift provided a lifeline for Berlin"; "she offered me a lifeline in my time of grief"