The phrase "already matured" is correct and usable in written English.
It can be used to describe something that has reached a state of maturity or development earlier than expected.
Example: "The plants have already matured, and we can begin harvesting them ahead of schedule."
Alternatives: "fully developed" or "already grown".
The 3D printer has already matured into a useful and versatile tool for making models, mock-ups and prototypes.
The '85 is already matured and not for laying down as it tends to go off quickly.
We decided that this genre is interesting to viewers, and we decided that our society has already matured to the stage of accurately evaluating this film".
A particular focus are the many intriguing experiments with 129Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications.
Kevin Faulk, the 31-year-old sage of the running backs, said Maroney had already matured from his rookie season, when, like most rookies, he expected his physical talent to sustain him as it had in high school and college.
With the credit markets virtually shut down, General Growth said it was unable to refinance the $3.3 billion in debt that had already matured or would be due this year.
Additional experiments could shed light on differences between the influence gap junctions have on neuronal networks that undergo maturation and the ones already mature.
Bryant, at 22, is already mature beyond his years.
Perhaps in the world's largest economy Facebook is already mature.
She seems like a star from a different era – a Sophia Loren, rather than a Cameron Diaz; already mature when she was 30 (she is now 39).
John Doerr, the venture capitalist, said, "Culturally, the Valley was already maturing before 9/11, but since then it's definitely developed a deeper respect for leaders and government institutions".
