puerilism
noun
pu·er·il·ism ˈpyu̇(-ə)r-ə-ˌli-zəm 
ˈpyu̇(-ə)r-ˌī-
: childish behavior especially as a symptom of mental illness
Word History
First Known Use
1924, in the meaning defined above
- running oak
- running off
- running off with
- running on
- running one's mouth
- running ornament
- running out
- running out of
- running out on
- running over
- running part
- running pine
- running rail
- running rigging
- running riot
- running rope
- running set
- running shoe
- running shooting
- running side
- running spider
- running start
- running stitch
- running story
- running strawberry-bush