To become mature and ready to eat or use, or to develop fully over time.
From Old English 'ripian,' related to 'ripe' meaning ready or mature, possibly related to 'reap' since ripe fruit is ready for harvest.
The biology of ripening is fascinating—fruits produce ethylene gas that triggers color change and sweetness, and this gas spreads through the fruit bowl, which is why one apple speeds up the others.
Complete word intelligence in one call. Free tier — 50 lookups/day.