1. a dancing, hopping, or leaping movement.
2. an abrupt movement or transition.
a. a sudden discontinuity in a line of descent.
b. a single mutation that drastically alters the phenotype.
4. Geology. intermittent, leaping movement of particles of sand or gravel, as from the force of wind or running water.
(From Latin saltare, meaning to leap. [Dictionary.com])
Saltation is the idea that a new species can emerge in one big mutational jump, rather than as a result of many tiny evolutionary steps. The idea isn't popular these days, as scientists have mostly debunked the hypothetical divide between macro and micro mutation. In evolutionary biology, it's colloquially referred to as the theory of the "hopeful monster," a charming term coined by German geneticist (and saltationist) Richard Goldschmidt (1878-1958).
Did reptiles dance, and dream of birds?