undulation

noun7

1. •
   An instance or act of undulating.

   • But the next undulation would raise us, showing the island ablaze in the sunlight, an emerald of dazzling beauty resting lightly on the bosom of the sea. — 1929
2. •
   A wavelike motion of the air; electromagnetic radiation.
3. •
   (old-fashioned) The distinctive motion of the matter within an abscess on being pressed when it is ripe for opening.
4. •
   A wavy appearance or outline; waviness.
5. •
   A wavelike curve; a smooth and regular rise and fall.
6. •
   A tremulous tone produced by a peculiar pressure of the finger on a string.
7. •
   (old-fashioned) A feeling as if of an undulatory motion about the heart.