Generally, a lacuna is a gap. The term may refer to:
- Lacuna (manuscripts), a missing section of text
- Lacuna (music), an extended silence in a piece of music
- Lacuna (linguistics), a lexical gap in a language
- Lacuna (law), the lack of a law or legal source addressing a situation
- Lacuna (histology), a small space containing an osteocyte in bone or chondrocyte in cartilage
- Lacuna (comics), a fictional Marvel Comics superhero and associate of X-Statix
- Lacuna model, a tool for unlocking culture differences or missing "gaps" in text
- Lacunar amnesia, in psychology, amnesia about a specific event
- Petrovsky lacuna, a region where the fundamental solution of a differential equation vanishes
- Lacuna Coil, an Italian hard rock/metal band
- Lacuna, Inc., a fictional company in the film Eternal Sunshine of the Spotless Mind
- The Lacuna, a 2009 novel by Barbara Kingsolver
- Lacuna, a character in the Xanth series of books by Piers Anthony
- In bone morphology, lacunae are spaces occupied by osteocytes that have migrated into and become trapped and surrounded by bone matrix.
