Is the liver a gland?
No, the liver is not a gland.
Actually Wikipedia is a good source for answers to such questions. It says regarding the liver: "The liver, an organ only found in vertebrates, detoxifies various metabolites, synthesizes proteins, and produces biochemicals necessary for digestion." Therefore, the liver is an organ.
Wikipedia says regarding glands, "A gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland)."
The conclusion, therefore, must be that the liver is not a gland.