* The muscles in her leg contracted involuntarily, causing a sharp pain. (meaning: to become smaller or tighter)
* The company contracted with a local firm to handle their marketing. (meaning: to make a formal agreement)
* The virus contracted rapidly, spreading through the population. (meaning: to become infected with a disease)
* The government contracted the construction of a new bridge. (meaning: to hire someone to do work)
As you can see, the meaning of "contract" as a verb depends on the context.