Antonyms for "pre-mature" include "delayed," "timely," "on time," "adequate," "appropriate," and "full-term," among others. Delayed refers to something that happens later than expected or planned, while timely means something that happens at the right time. On time is another synonym for timely, while adequate refers to something that is sufficient or suitable. Appropriate means something that is suitable or fitting, while full-term is used to describe something that is completed within the expected or required time frame. These antonyms provide a range of options depending on the context in which the word "pre-mature" is used.