noun.
The physical science and technology of the static and dynamic behavior of fluids.
The Century Dictionary and Cyclopedia
noun.
That branch of engineering science which treats of the motion of liquids, the laws by which it is regulated, and the application of these principles to machinery, marine engineering, etc.
the GNU version of the Collaborative International Dictionary of English
noun.
That branch of science, or of engineering, which treats of fluids in motion, especially of water, its action in rivers and canals, the works and machinery for conducting or raising it, its use as a prime mover, and the like.