Apple doesn’t get the exclusive rights to the term multi-touch. The company submitted an application to the patent office of the US, but did not get it. The request was not about the technology, but solely about the word.
The application for the trademark was done several years ago. On January 9, 2007, the day the first iPhone saw the light, Apple asked for a monopoly on the name. The U.S. trademark office needed several years to conclude that the term is too general and descriptive. Therefore, other companies say their devices "multitouch" support.
The iPhone was the first device that supports multitouch. This technique allows a touch screen to be used with multiple fingers. Thus, zooming in and out by moving two fingers closer together or moving apart is made possible. The technique was then adopted by many competitors. Nowadays almost all smartphones support multitouch.
Source: Macrumors.com