A line that connects two opposite corners of a figure.
From Latin, from Greek dia-, 'apart' or 'across' + -gon, 'angle,' meaning 'from angle to angle.' Greek -gon derives from Indo-European genu-, 'knee, angle'.
Related mathematical terms
* For terms related to -gon, see: Orthogonal, -gon, Pentagon, Hexagon, Octagon, Trigonometry
* For terms related to -dia, see: Diameter
Other related words
knee (the kn of knee is the gn of genu in genuflect), kneel, genuflect, genuine (sworn as truth on bended knee!), -gon (in orthogonal where ortho- means 'right'; pentagon, hexagon, etc.)