The phrase "entity in itself" is correct and usable in written English.
It typically refers to something that is considered to have a unique and individual existence and character. For example, one might say "The relationship between the two countries is an entity in itself, with its own unique dynamics."
But Glastonbury is such an entity in itself, I wouldn't be able to recapture it, and I wouldn't want to try".
Turns out it's one of those films so big, so hot, so throbbing*, that the mere trailer is released as an entity in itself.
In that sense I suppose it [Africa Express] has had some very positive effects, but it isn't really an entity in itself, it doesn't claim ownership of anything.
For the poet, though, the unknown is an entity in itself, its history and maps and customs arising from imaginative necessity: to declare somewhere unknown is, in rhetorical terms, a strategy for knowing something about it.
It is designed, as Adam Thirlwell wrote in a piece for Granta ahead of its Spanish-language special, to self-destruct; as an entity in itself, it can't last much longer than the present moment.
"Every phrase, every vocal gesture and every theatrical move has been painstakingly considered," Bernard Holland wrote in The New York Times, "making this Carmen more a collection of calculated details than an entity in itself.
It also encourages seeing relations between entities as being unimportant to what the entity is "in itself".
If the artwork is an autonomous entity that stands-in-itself and does not refer to anything outside itself, what of art's speculative capacity to refer to other complexes beyond its immediate horizon?
He submits that the soul must be an incorporeal, intellectual entity, subsistent in itself, immortal, and yet designed to be one with the body.
This lesion is recognized as a separate entity which in itself is not malignant but may be a precursor of adenocarcinoma.
Patience is not an entity in and of itself, but is a process, the act of learning to embrace a state of mind.
