The American Heritage® Dictionary of the English Language, 4th Edition
n. A dramatic or literary form of discourse in which a character talks to himself or herself or reveals his or her thoughts without addressing a listener.
n. A specific speech or piece of writing in this form of discourse.
n. The act of a character speaking to himself so as to reveal his thoughts to the audience.
n. A speech or written discourse in this form.
v. To issue a soliloquy.
the GNU version of the Collaborative International Dictionary of English
n. The act of talking to one's self; a discourse made by one in solitude to one's self; monologue.
n. A written composition, reciting what it is supposed a person says to himself.
The Century Dictionary and Cyclopedia
n. A talking to one's self; a discourse or talk by a person who is alone, or which is not addressed to any one even when others are present.
n. A written composition containing such a talk or discourse, or what purports to be one.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a (usually long) dramatic speech intended to give the illusion of unspoken reflections
n. speech you make to yourself
Word Usage
"The lengthy trumpet solo near the end, which the program notes advise is an orchestrated soliloquy from the opera on a John Donne poem, was only the most prominent example."