• Etymology Today from M-W: lacuna \lu-KOO-nuh or luh-KYOO-nuh\
*1 : a blank space or a missing part : gap
2 : a small cavity, pit, or discontinuity in an anatomical structure

Exploring the etymology of "lacuna" involves taking a plunge into the pit -- or maybe a leap into the "lacus" (that's the Latin word for "lake"). Latin speakers modified "lacus" into "lacuna," and used it to mean "pit," "cleft," or "pool." English speakers borrowed the term in the 17th century. Another English word that traces its origin to "lacuna" is "lagoon," which came to us by way of Italian and French.

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