1.
If you cover something or someone up , you put something over them in order to protect or hide them.
He fell asleep in the front room so I covered him up with a duvet.
PHRASAL VERB : V n P , also V P n (not pron)
2.
If you cover up something that you do not want people to know about, you hide the truth about it.
He suspects there’s a conspiracy to cover up the crime...
They knew they had done something terribly wrong and lied to cover it up...
How do we know you’re not just covering up for your friend?
PHRASAL VERB : V P n (not pron) , V n P , V P for n
see also cover-up