For all adjectives—both i-adjectives and na-adjecitves—we can turn them into nouns with the particle さ.

For i-adjectives we replace い and さ.

かなしい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] かなしさ
Sad [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Sadness
たのしい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] たのしさ
Enjoyable [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] amusement
たかい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] たか
Tall [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Height
むずかしい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] むずかしさ
Difficult [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Difficulty
からい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] から
Hot/spicy [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Spiciness/Hotness

For na-adjectives we add さ.

複雑ふくざつ [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] 複雑ふくざつ
Complex [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Complexity
透明とうめい [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] 透明とうめい
Transparent [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Clearness
便利べんり [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] 便利べんり
Convenient [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Convenience
大切たいせつ [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] 大切たいせつ
Important [mks_icon icon=”fa-long-arrow-right” color=”#000000″ type=”fa”] Importance
このビルのたかさは250メートルです。
The height of this building in 250 meters.
挑戦ちょうせんしてみれば試験しけんむずかしさがわかる。
If you give it a try you’ll understand the difficulty of the exam.

For a limited number of i-adjectives we can also create a noun with the particle み. Unfortunately, there is no set rule as to which i-adjectives can be nominalized with this particle but some of the most commonly heard are given below.

かなしみ
Sadness
から
Spiciness
いた
Pain (hurt)
あま
Sweetness
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