1. Greatness of size; magnitude.
2. Fullness; copiousness.
3. Breadth or range, as of intelligence.
4. Astronomy. The angular distance along the horizon from true east or west to the intersection of the vertical circle of a celestial body with the horizon.
5. Physics. The maximum absolute value of a periodically varying quantity.
6. Mathematics.
   1. The maximum absolute value of a periodic curve measured along its vertical axis.
   2. The angle made with the positive horizontal axis by the vector representation of a complex number.
7. Electronics. The maximum absolute value reached by a voltage or current waveform.

[Latin amplitūdō, from amplus, large.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.