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

• transitive verb To subject or allow to be subjected to an action, influence, or condition.
• transitive verb To subject (a photographic film, for example) to the action of light.
• transitive verb To deprive of shelter or protection; lay open to danger or harm.
• transitive verb To make visible: synonym: show.
• transitive verb To make known (something discreditable).
• transitive verb To reveal the guilt or wrongdoing of.
• transitive verb To engage in indecent exposure of (oneself).

from The Century Dictionary.

• To place or set forth so as to be seen or known; lay open to view; lay bare; uncover; reveal: as, to expose a thing to the light; to expose a secret.
• To place on view; exhibit; show: as, to expose goods for sale.
• To present to the action or influence of something: as, in photography, to expose a sensitized plate to the action of the actinic rays of light.
• To place or leave in an unprotected place or state; specifically, to abandon to chance in an open or unprotected place: as, among the ancient Greeks it was not uncommon for parents to expose their children.
• To place in the way, as of something which it would be better to avoid; subject, as to some risk; make liable: as, vanity exposes a person to ridicule; the movement exposed him to the danger of a raking fire in his flanks.
• To make known the actions or character of; reveal the secret or secrets of; lay open to comment, ridicule, reprehension, or the like, by some revelation: as, to expose a hypocrite or a rogue; to expose an impostor.
• To expound, as a theory.

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

• transitive verb To set forth; to set out to public view; to exhibit; to show; to display
• transitive verb To lay bare; to lay open to attack, danger, or anything objectionable; to render accessible to anything which may affect, especially detrimentally; to make liable
• transitive verb To deprive of concealment; to discover; to lay open to public inspection, or bring to public notice, as a thing that shuns publicity, something criminal, shameful, or the like.
• transitive verb To disclose the faults or reprehensible practices of; to lay open to general condemnation or contempt by making public the character or arts of.

from , Creative Commons Attribution/Share-Alike License.

• verb transitive to uncover, make visible, bring to daylight, introduce to
• verb transitive to subject photographic film to light thus ruining it or taking a picture if controlled
• verb transitive to abandon, especially an unwanted baby in the wilderness

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

• verb expose to light, of photographic film
• verb expose while ridiculing; especially of pretentious or false claims and ideas
• verb abandon by leaving out in the open air
• verb put in a dangerous, disadvantageous, or difficult position
• verb remove all or part of one's clothes to show one's body
• verb disclose to view as by removing a cover
• verb make known to the public information that was previously known only to a few people or that was meant to be kept a secret
• verb expose or make accessible to some action or influence
• verb to show, make visible or apparent
• noun the exposure of an impostor or a fraud