Many languages have a suffix (or some other alteration) that gives a pejorative meaning to a word. For example, in Spanish:
pájaro "bird" + -aco → pajarraco "big, ugly bird"
What do you call a suffix that gives an "anti-pejorative" meaning to a word? For example, imagine if you could do this:
pájaro "bird" + -iñalo → pajariñalo "beautiful bird"