Undulatory Theory

Undulatory Theory, the theory that light is due to vibrations or undulations in the ether as the medium through which it is transmitted from its source in a luminous body.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Undine * Unearned Increment
Uma
Umballa
Umbria
Umlaut
Una
Uncial Letters
Uncle Sam
Unconscious, The
Understanding, The
Undine
Undulatory Theory
Unearned Increment
Unicorn
Uniformity, Act Of
Unigenitus, The Bull
Union, Federal
Union, The
Union Jack
Unionists
Unitarians
United Brethren