v. mod·u·lat·ed, mod·u·lat·ing, mod·u·lates
1. To regulate or adjust to a certain degree: physiological mechanisms that modulate the body's metabolic rate.
2. To change or vary the pitch, intensity, or tone of (one's voice or a musical instrument, for example).
a. To vary the frequency, amplitude, phase, or other characteristic of (electromagnetic waves).
b. To vary (electron velocity) in an electron beam.
4. Biochemistry To act on (a receptor, for example) as an activator, an inhibitor, or both.
To move from one key or tonality to another by means of a melody or chord progression.
[Latin modulārī, modulāt-, to measure off, to regulate, from modulus, diminutive of modus, measure; see med- in the Appendix of Indo-European roots.]
modu·la′tive, modu·la·to′ry (-lə-tôr′ē) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.