refined and tasteful in appearance or behavior or style; "elegant handwriting"; "an elegant dark suit"; "she was elegant to her fingertips"; "small churches with elegant white spires"; "an elegant mathematical solution--simple and precise and lucid"
From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
(From Mathematics) Combining simplicity, power, and a certain ineffable grace of design. Higher praise than "clever", "winning" or even cuspy.
The French aviator, adventurer, and author Antoine de Saint-Exup'ery, probably best known for his classic children's book "The Little Prince", was also an aircraft designer. He gave us perhaps the best definition of engineering elegance when he said "A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away."