Look at these examples

This is a tricky subject, because nobody seems to agree on which words are just nouns and which ones are nouns and verbs. The truth is that language evolves and words which once were used only as nouns begin being used as verbs. The hybrid verbs often describe the action of being or obtaining the object described by the noun. Some examples of nouns which are used as verbs are: "contact," "impact," "focus," "parent," "medal," and "liaison." Just to take the guesswork out of it, we will tell you what the verb-forms of these nouns are supposed to mean, which ones you may and may not use, and why you may or may not use them.

Contact: To establish contact with something else. You may use this noun as a verb, because it is so prevalent that you'll end up sounding very strange if you don't use it.

Impact: To make or have an impact on something. You may not use this noun as a verb. It sounds horribly clumsy and many people find its use as a verb aesthetically offensive. You have been warned.

Focus: To narrow or clarify one's figurative focus to concentrate on a particular point. You may use this noun as a verb. Once again, it's just so common that you might as well bow to the mindless masses.

Parent: To behave as a parent would. You may not use this noun as a verb. This is just laziness, and it sounds so idiotically new-age that it makes us ill.

Medal: To receive a medal, usually in the Olympics. Of course you may not use this noun as a verb. How horrible.

Liaison: To attend a liaison. You may use this noun as a verb. The military uses it extensively, and its members will not listen to us no matter what we say. It is also an anglicized noun from French, so what harm will a little more tinkering do to it?

Use your judgment

Modern dictionaries, particularly the Merriam Webster dictionary (http://www.m-w.com/dictionary.htm), will tell you that it is all right to use words just about any way you might ever imagine. This is because they suffer from Samuel Johnson's fear of missing some word or use of a word in their attempts to be comprehensive. It is perfectly acceptable for you to disagree with the writers of dictionaries and say "Just because some idiot thinks it's okay to use ‘medal' as a verb doesn't mean I'm going to join in." If you look at a dictionary entry carefully, you'll often see that the word you're looking at was used exclusively as a noun up until 1983 or something like that. This is a good sign that only those with no taste would use the noun as a verb. Of the above examples, we only use "contact" as a verb, and we only use that because of pressure from past employers and professors. You might choose to be less sensitive to this issue than we are, but you'd better hope your written work is never evaluated by someone who agrees with us.