1. happening too soon: occurring, existing, or developing earlier than is expected, normal, or advisable It would be premature to suggest that there is a link between these events.
2. born too early: born before completing the normal gestation period, or, for a human infant, weighing less than 2.5 kg (5 lb 8 oz) at birth
[Early 16th century. < Latin praematurus "ripening too early" < maturus "ripe"]