IAU new definition of planet

The definition of planet set in 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:

♤ is in orbit around the Sun,

♤ has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and

♤ Has "cleared the neighbourhood" around its orbit. For this they become the dominant gravitational body in their orbit in the Solar System. Pluto lacks it.

Any object if meet the first two criteria but doesn’t meet the 3rd criteria is considered a

dwarf planet. Thus Pluto is a dwarf planet.