word choice - Alternative for "full-fledged"

I am looking for an alternative for "full-fledged".

Mister X systematised its use and meaning, and developed the notion
into a full-fledged concept of ...

The context is academic, but not related to zoology. Its a paper about language and semantics, and I do not like the phrase "full-fledged" in those contexts, so I guess I have two questions:

1. Is this expression ok in this context


2. Notwithstanding Question #1, are there suitable alternatives?

Answer

The other substitutes available for full-fledged can be :

completely developed, developed, experienced, full-grown, grown,
grown-up, in full bloom, mature, qualified, schooled, seasoned,
skilled, trained, well-developed

In mine view mature will be more appropriate.

i.e.

Mister X systematized its use and meaning, and developed the notion into a mature concept...