Nummy requires less
lip/
tongue/
teeth coordination and
movement than
Yummy, and so
kids are generally able to make that
sound much
sooner than yummy.
It can be used and changed as needed. When feed an
infant, for instance, one might (as the
spoon nears the mouth) say, "Mmmm! Yummy!
Num num num num num..." until the child opens his/her mouth and eats the
food.