physics

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The science of matter and energy and of interactions between the two, grouped in traditional fields such as acoustics, optics, mechanics, thermodynamics, and electromagnetism, as well as in modern extensions including atomic and nuclear physics, cryogenics, solid-state physics, particle physics, and plasma physics.
• noun Physical properties, interactions, processes, or laws.
• noun Archaic The study of the natural or material world and phenomena; natural philosophy.

from The Century Dictionary.

• noun Natural philosophy; experimental philosophy; the science of the principles operative in inorganic nature; the science of forces or forms of energy. ; ;

from the GNU version of the Collaborative International Dictionary of English.

• noun The science of nature, or of natural objects; that branch of science which treats of the laws and properties of matter, and the forces acting upon it; especially, that department of natural science which treats of the causes (as gravitation, heat, light, magnetism, electricity, etc.) that modify the general properties of bodies; natural philosophy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The branch of science concerned with the study of properties and interactions of space, time, matter and energy.
• noun Of or pertaining to the physical aspects of a phenomenon or a system, especially those studied in physics.
• noun Plural form of physic.
• verb Third-person singular simple present indicative form of physic.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the physical properties, phenomena, and laws of something
• noun the science of matter and energy and their interactions