noun, used as a suffix, noun
itself; the thing itself; in itself
Most often used after a noun as X自体, focusing on X itself apart from related circumstances, consequences, or surrounding factors.
この計画自体に問題はない。
There is no problem with the plan itself.
値段自体は高くないが、送料がかかる。
The price itself is not high, but shipping costs extra.
noun
one's own body; oneself
Rare as a modern independent noun meaning one's own body or self; learners will usually encounter 自体 in the suffix-like 'itself' sense instead.
古い文章では、「自体」が自分自身や自分の体を指すことがある。
In older writing, 自体 can refer to oneself or one's own body.
adverb
originally; naturally; by nature; from the start
Rare adverbial use meaning that something is so from the beginning or by its nature; in ordinary modern Japanese, もともと, 本来, or 生まれつき is usually clearer.
「自体」を副詞として使うと、まれに「もともと」「はじめから」という意味になる。
When 自体 is used as an adverb, it can rarely mean 'originally' or 'from the start.'
Also means 'self/itself,' but 自身 often emphasizes the person or thing as the actor or owner, while 自体 focuses on the matter or object itself apart from surrounding factors.
A stronger expression for 'the very thing itself' or 'exactly that'; it can sound more emphatic or descriptive than the relatively neutral suffix 自体.
The normal modern adverb for 'originally' or 'from the start'; it is much more common and natural than the rare adverbial use of 自体.
A Sino-Japanese compound written with 自, 'self/own,' and 体, 'body, form, substance.' This component meaning fits both the common 'itself' use and the rarer 'one's own body' sense; the exact historical development of the adverbial use is uncertain.