na-adjective
Formal or literary adjectival noun meaning 'in that manner' or 'such'. Often used in set phrases like さようなら (goodbye, from さようならば 'if it be so').
さようならは「左様ならば」の略だと言われている。
It is said that さようなら is an abbreviation of 左様ならば (if it be so).
彼の意見はさようではない。
interjection
Formal interjection used to express agreement or acknowledgment, similar to 'that is correct' or 'just so'.
「この書類で間違いありませんか?」「さようでございます。」
"Is this document correct?" "That is right."
interjection
let me see; well now
Formal interjection used when pausing to think or recall something, similar to 'let me see' or 'well now'. Often used in polite or old-fashioned speech.
さよう、何から話しましょうか。
Well now, where shall I begin?
His opinion is not so.
Derived from classical Japanese さ (that way) + 様 (よう, manner/appearance). The kanji 左様 and 然様 are ateji; the word is now almost exclusively written in kana.