Here's the background: in QED, there is one charge, which we're all familiar with, the electric charge. Mathematically we can call the charge C, such that using + to denote its regular charge and - to denote its anticharge:
[eqn]C^+ + C^- = 0[/eqn]
In other words, a charge added to its corresponding anticharge yields 0 charge, or neutral. Compactly, we just call these charges [math]+[/math] and [math]-[/math]. Moving on to QCD, we have three charges which function in the following way:
[eqn] \begin{align}
C_1^+ + C_1^- &= 0 \\
C_2^+ + C_2^- &= 0 \\
C_3^+ + C_3^- &= 0 \\
C_1^+ + C_2^+ + C_3^+ &= 0 \\
C_1^- + C_2^- + C_3^- &= 0
\end{align}
[/eqn]
Where the first three equations represent simple mesons, which follow the rules we expect: charge plus anticharge equals neutral. The last two equations represent baryons, with the first representing real baryons and the second being anti-baryons. Now three "positive" charges yield a neutral charge.
Feynman called these physicists idiots for calling it color. What say you, /sci/? Any better names?