perturbation

He turned his thesis into the book Geometric Perturbation Theory in Physics on the new developments in differential geometry.

Say your portfolio is worth a third less than before this recession or crash or perturbation or whatever you want to call it.

At times there are periodic attacks of mental perturbation that may become true insanity.

She picked up her parasol, and resumed her journey in some perturbation of mind, reflecting on the utter rudeness of the deer.

I had an idea that she would shrink from me or show some perturbation; but I was never more mistaken in my life.

Agatha went up to her mistress in a state of great perturbation, and the cook also hurried away to her bedroom.

The frown of bewilderment was deeper now––the perturbation turned anxious.