Generally speaking a Lacuna is a GAP

* 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) is the lack of law or of a legal source addressing a situation
* Lacuna (histology), a small space containing an osteocyte in bone or chondrocyte in cartilage
* Lacuna model, a tool for unlocking culture differences or missing "gaps" in text
* Lacunar amnesia, in psychology, amnesia about a specific event
* Lacuna (geology), a large gap in the stratigraphic record, sometimes called a hiatus or unconformity