Lacuna \ lə-ˈkü-nər a little lake. Or a pause, gap or break in a text, painting or musical work.
Latin lacūna: “little lake”.
Word of the day: “lacuna”- in a manuscript, an inscription, or the text of an author: a hiatus, blank, missing portion (OED n.1)
A word borrowed from Latin in the 17th Century by the English by way of Italian and French.
French: lacune A gap in personal knowledge (for a pupil or a student): “avoir des lacunes en mathématiques”. Also closely related to lagune a coastal lake.