1727, "grown ripe," from Latin maturescentem (nominative maturescens), present participle of maturescere "be ripe, ripen," from maturus "ripe" (see mature (v.)) + inchoative suffix -escere.
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for maturescent
Maturescent, mat-ū-res′ent, adj. becoming ripe: approaching maturity.