～さ

About

When さ attaches to an adjective it turns it into a noun. さ nouns describe something's objective, measurable qualities.

E.g.

熱あつい "hot" → 熱あつさ "heat"

優やさしい "kind" → 優やさしさ "kindness"

大切たいせつ "important" → 大切たいせつさ "importance"

さ can also be used with auxiliary verbs such as たい and らしい.

Summary

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  Attach さ to an adjective, or certain auxiliary verbs, to form a noun