Is 100.2 considered a fever for an adult?

Of course: It also depends from where the body temperature is obtained. If obtained orally, or from forehead, we usually add one more degree so that 100.2 becomes 101.2. Rectal temperature is more accurate because it is the core body temperature.

More or less, yes: Normal body temperature is 98.6. That said, many people will normally run as low as 96.7 in the morning, and can reach 98 or 99 by mid-afternoon. For most of us, though, a body temp above about 99, 5 is probably a low grade temp, which can be caused by a mild infectious or chronic inflammatory process. A "fever, " per se, is probably best defined as a core body themperature greater than 101.5'.