Signum is Latin for "sign" and may refer to:
- Signum function or sign function in mathematics
- Signum, a part of the female Lepidoptera genitalia
- Signum (album), a 1995 album by German industrial music artist P·A·L
- Signum Framework
- Integra Signum, a (defunct) Swiss railroad signaling company
- Signum (magazine), a German literary magazine
- Signum (musical group), a trance music group
- Signum (Nanoha), a character from the Magical Girl Lyrical Nanoha series
- Opel Signum, a General Motors vehicle model
- Signum Records, a classical record label
- Signum (typeface), a 1955 typeface designed by Georg Trump for the Weber Typefoundry