Collocations for rejection - noun

outright, total, wholesale
explicit
deliberate
knee-jerk
There is often a knee-jerk rejection of new ideas.

fear
Children who have had bad experiences fear rejection.

risk
cope with, deal with, handle, take
It takes a strong personality to cope with rejection.

letter, slip
a publisher's rejection slip

rejection by
the rejection of the child by its mother

fear of rejection
feelings of rejection
the rejection of an idea, a proposal, a theory, etc.