Definitions
1.NounAny place that is optimal for obtaining a certain desirable effect or result.
2.NounAny set of conditions that is optimal for obtaining a certain desirable effect or result.
3.NounThe clitoris, prostate gland, or other internal center of sexual pleasure.
4.NounAny of several places on a bat, racquet, etc., with which to hit a ball, resulting in the latter rebounding with some optimal desirable effect, such as minimum vibration or maximum velocity."He hit the ball with the sweet spot, resulting in a gapper."
5.Noun(The addition of quotations indicative of this usage is being sought:) The spot of a lens in where image clarity is perfectly clear and sharp.