whisper

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

• noun Soft speech produced without using the full voice.
• noun Something uttered very softly.
• noun A secretly or surreptitiously expressed belief, rumor, or hint.
• noun A low rustling sound.
• intransitive verb To speak softly.
• intransitive verb To speak quietly and privately, as by way of gossip, slander, or intrigue.
• intransitive verb To make a soft rustling sound.
• intransitive verb To utter very softly.
• intransitive verb To say or tell privately or secretly.

from The Century Dictionary.

• To speak without uttering voice or sonant breath; speak with a low, rustling voice; speak softly or under the breath; converse in whispers: often implying plotting, evil-speaking, and the like.
• To make a low, rustling sound, like that of a whisper.
• To utter in a low non-vocal tone; say under the breath; state or communicate in whispers: often implying plotting, slanderous talk, etc.
• To address or inform in a whisper or low voice, especially with the view of avoiding publicity: elliptical for whisper to.
• noun The utterance of words with the breath not made vocal; a low, soft, rustling voice.
• noun A whispered word, remark, or conversation.
• noun A secret hint, suggestion, or insinuation.
• noun A low, rustling sound of whispering, or a similar sound, as of the wind.
• noun Specifically, in medicine, the sound of the whispering voice transmitted to the ear of the auscultator placed against the chest-wall.

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

• intransitive verb To speak softly, or under the breath, so as to be heard only by one near at hand; to utter words without sonant breath; to talk without that vibration in the larynx which gives sonorous, or vocal, sound. See Whisper, n.
• intransitive verb To make a low, sibilant sound or noise.
• intransitive verb To speak with suspicion, or timorous caution; to converse in whispers, as in secret plotting.
• transitive verb To utter in a low and nonvocal tone; to say under the breath; hence, to mention privately and confidentially, or in a whisper.
• transitive verb Archaic To address in a whisper, or low voice.
• transitive verb obsolete To prompt secretly or cautiously; to inform privately.
• noun A low, soft, sibilant voice or utterance, which can be heard only by those near at hand; voice or utterance that employs only breath sound without tone, friction against the edges of the vocal cords and arytenoid cartilages taking the place of the vibration of the cords that produces tone; sometimes, in a limited sense, the sound produced by such friction as distinguished from breath sound made by friction against parts of the mouth. See Voice, n., 2, and Guide to Pronunciation, §§ 5, 153, 154.
• noun A cautious or timorous speech.
• noun Something communicated in secret or by whispering; a suggestion or insinuation.
• noun A low, sibilant sound.

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

• noun The act of speaking in a quiet voice, especially, without vibration of the vocal cords.
• noun usually in plural A rumor.
• noun figuratively A faint trace or hint (of something).
• noun Internet A private message to an individual in a chat room.
• verb To talk in a quiet voice.

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

• noun a light noise, like the noise of silk clothing or leaves blowing in the wind
• verb speak softly; in a low voice
• noun speaking softly without vibration of the vocal cords