the.com/immaturity

means The state of lacking the emotional or mental development expected for one's age, especially a tendency to react rather than reflect.

from From Latin immaturus, 'not ripe' — im- (not) plus maturus (ripe, timely), the same root that gives us 'mature.' The metaphor is agricultural: a person, like fruit, can be picked before they're ready, still green on the inside no matter how big they've grown on the outside.