Hypocrisy literally means criticism of others, by a standard one does not apply to oneself. It is hypocritical to use a double standard which strictly applies a rule to one group of people, while exempting or excusing another group.
It is difficult to present an example which both liberals and conservatives will accept, since each side accuses the other of hypocrisy while insisting on its own integrity.
A hypothetical example must suffice: Suppose a politician criticizes an opponent for "catering to special interests," rather than saying and doing things which benefit every constituent. If this politician is also "in the pocket" of special interests, it would be hypocritical to critique an opponent for doing the same.