み

「み」is added after an adjective to form a noun indicating a state or quality.
The suffix 「み」can only be added to certain adjectives like 悲しい (sad), 楽しい (fun), 弱い (weak), 苦しい (painful)...
Many adjectives can be nominalized by adding both the suffix 「さ」and the suffix 「み」, but they have slightly different meanings.
The suffix 「さ」emphasizes the degree and is objective. The adjective it accompanies describes things that can be measured, such as size, weight... Or if it's an adjective describing emotions,「さ」expresses a general feeling that many people can perceive about an object, event, and can somewhat share with each other.
On the other hand, the suffix 「み」emphasizes the quality, state, and is subjective. This quality, state is something that needs to be experienced firsthand to know, such as taste, warmth... or emotions that only individuals can feel and thus are difficult to share with others.
Example: 強さ (strength) and 強み (strong point); 甘さ (sweetness) and 甘み (sweetness)...