When something smells high heaven, it means that it is emitting a strong, unpleasant odor. There are several synonyms you can use to describe this pungent smell. For instance, you can say that the odor is malodorous, foul-smelling, or putrid. You can also use the term stinky, which is a common and informal way to describe an unpleasant smell. Another synonym is noxious, which implies that the smell is harmful and toxic. Other words that can be used include rancid, rank, and acrid. All these terms effectively convey the notion of a bad odor and can be used interchangeably with "smell high heaven".