Longum may refer to:
People Leif Longum (1927–1997), a Norwegian essayist and literary researcher
Places Longum, Agder, a village in Arendal municipality in Agder county, Norway
Science Longum means "long" in Latin, so it has been used in the scientific names of several living things: Bifidobacterium longum, a type of bacteria of the human digestive system Glottiphyllum longum, a species of succulent plant Piper longum, a flowering vine also known as Indian long pepper Methylobacterium longum, a facultative methylotrophy bacteria Xanthophyllum longum, a tree in the family Polygalaceae
Other Longum is type of syllable weight in poetry