Noun

1. The act of lengthening, or the state of being lengthened; protraction; extension.
2. That which lengthens out; continuation.
3. The ratio of the extension of a material to the length of the material prior to stretching.
4. Removal to a distance; withdrawal; a being at a distance; distance.
5. The angular distance of a planet from the sun; as, the elongation of Venus or Mercury.