Tint
Tint is the second white balance slider, alongside temperature: it controls the balance between green and magenta. You use it to remove a green or purple cast that lingers after you've set the temperature right. Together, temperature and tint make up your full white balance.
A green cast (from fluorescent light, for example) goes away by sliding tint toward magenta. Don't forget tint when your photo still looks 'off' after setting temperature: often this is exactly where it hides. The white balance eyedropper sets both sliders in one click when you click something neutral. For creative work you can let tint drift on purpose, like a hint of magenta for a warm sunset.
Related terms
Prefer a look in one click?
The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.