n.
an attempt to prevent people discovering the truth about a serious mistake or crime: he is alleging a cover-up and calling for an investigation
Oxford Dictionary
n.
an attempt to prevent people's discovering the truth about a serious mistake or crime: he is alleging a cover-up and calling for an investigation
Oxford American Dictionary
ph.
put something on, over, or around something, especially in order to conceal or disguise it
Oxford American Dictionary
ph.
try to hide the fact of illegal or illicit activity
Oxford Dictionary