What word or phrase does your mother always say?
"blank or missing portion in a manuscript," 1660s, from Latin lacuna "hole, pit," diminutive of lacus "pond, lake" (see lake (n.1)). The Latin plural is lacunae. Related: Lacunal; lacunar; lacunose.
lacuna la·cu·na (lə-kyōō'nə)
n. pl. la·cu·nas or la·cu·nae (-nē)
An anatomical cavity, space, or depression, especially in a bone.
An empty space or a missing part; a gap; a defect.
An abnormal space between the strata or between the cellular elements of the epidermis.
See corneal space.