さConverting adjectives to nouns

Fun Fact

It is thought that this suffix originally stemmed from the kanji 差(さ) (meaning 'distinction'), and was used for highlighting things that were distinctive features of something. In this way, さ is also sometimes used after the dictionary form of verbs, to highlight a distinct point in time that something happens.

However, this use of the suffix is far less common in modern Japanese, and is known as 'poetic language'. It was primarily used during Japan's 'middle ages', which spanned from (around) 1100, until close to the end of the 1500's.