resonance

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

• noun Intensification and prolongation of sound, especially of a musical tone, produced by sympathetic vibration.
• noun Intensification of vocal tones during articulation, as by the air cavities of the mouth and nasal passages.
• noun Medicine The sound produced by diagnostic percussion of the normal chest.
• noun Richness or significance, especially in evoking an association or strong emotion.
• noun Physics The increase in amplitude of oscillation of an electric or mechanical system exposed to a periodic force whose frequency is equal or very close to the natural undamped frequency of the system.
• noun Physics A subatomic particle having too short a lifetime to be observed directly and whose existence is inferred from a peak in the energy distribution of its decay products.
• noun Chemistry The property of a compound having simultaneously the characteristics of two or more structural forms that differ only in the distribution of electrons. Such compounds are highly stable and cannot be properly represented by a single structural formula.

from The Century Dictionary.

• noun In electricity, the condition of an alternating electric circuit in which the capacity reactance equals or approximately equals the inductive reactance.
• noun In psychology: A term applied, in the James-Lange theory of emotion, to the complex of bodily changes reflexly aroused by the object which excites emotion. “The changes are so indefinitely numerous and subtle that the entire organism may be called a sounding-board.”
• noun By extension of meaning, the sympathetic arousal in oneself, as if by echo, of a state of feeling whose manifestations one is observing in another, or the course of which one is tracing in imagination, but of which one has had no direct and first-hand experience.
• noun The act of resounding, or the state or quality of being resonant.
• noun In acoustics:
• noun The prolongation or repetition of sound by reflection; reverberation; echo
• noun The prolongation or increase of sound by the sympathetic vibration of other bodies than that by which it is originally produced.
• noun In medicine, the sound evoked on percussing the chest or other part, or heard on auscultating the chest while the subject of examination speaks either aloud or in a whisper.

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

• noun The act of resounding; the quality or state of being resonant.
• noun (Acoustics) A prolongation or increase of any sound, either by reflection, as in a cavern or apartment the walls of which are not distant enough to return a distinct echo, or by the production of vibrations in other bodies, as a sounding-board, or the bodies of musical instruments.
• noun (Physics) A phenomenon in which a vibration or other cyclic process (such as tide cycles) of large amplitude is produced by smaller impulses, when the frequency of the external impulses is close to that of the natural cycling frequency of the process in that system.
• noun (Electronics) An electric phenomenon corresponding to that of acoustic resonance, due to the existance of certain relations of the capacity, inductance, resistance, and frequency of an alternating circuit; the tuning of a radio transmitter or receiver to send or detect waves of specific frequencies depends on this phenomenon.
• noun (Med.) the sound heard on percussing over the lungs.
• noun (Med.) the sound transmitted to the ear when auscultation is made while the patient is speaking.

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

• noun The condition of being resonant.
• noun A resonant sound, echo
• noun figuratively Something that evokes an association, or a strong emotion.
• noun physics The increase in the amplitude of an oscillation of a system under the influence of a periodic force whose frequency is close to that of the system's natural frequency.
• noun nuclear physics A short-lived subatomic particle that cannot be observed directly.
• noun An increase in the strength or duration of a musical tone produced by sympathetic vibration.
• noun chemistry The property of a compound that can be visualized as having two structures differing only in the distribution of electrons.

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

• noun having the character of a loud deep sound; the quality of being resonant
• noun an excited state of a stable particle causing a sharp maximum in the probability of absorption of electromagnetic radiation
• noun a vibration of large amplitude produced by a relatively small vibration near the same frequency of vibration as the natural frequency of the resonating system
• noun a relationship of mutual understanding or trust and agreement between people
• noun the quality imparted to voiced speech sounds by the action of the resonating chambers of the throat and mouth and nasal cavities