1. The very slight gravitational field experienced by a mass that is far removed from any other mass, as in intergalactic or interstellar space.
2. A condition, such as a free fall or orbital motion, in which acceleration of an object causes it to appear weightless even in the presence of a strong gravitational force.
3. A minute shift in the earth's gravitational field that can occur through geologic processes in a region, such as the movement of the earth's crust along fault lines.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.