\begin{definition}[Definition:Dwarf Planet]
A '''dwarf planet''' is a celestial body which orbits a star (or the remains of a star) that:
:$(1): \quad$ has enough mass so that its own gravitational field makes it approximately spherical
:$(2): \quad$ does not have enough mass to trigger thermonuclear fusion
:$(3): \quad$ has not cleared its neighbouring region of planetesimals.
\end{definition}