Actually, if my memory serves me correctly 14:1 is the perfect stoichiometric ratio for air fuel combustion.

This is also the ratio that will give you the most power per quantity of fuel assuming you can use this ratio without detonation.

The only reason to go any lower is to reduce the risk of detonation in high compression or forced induction motors.

For that reason I would say it is not lean, but just not rich enough for use under adverse conditions.

If your view of mild compression is less than 10:1 that a/f ratio would be just fine for a n/a motor and should be pretty close to what all modern closed loop emissions motors are trying to keep their mix rate at.