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n. pl. la·cu·nae (-nē) or la·cu·nas
1. An empty space or a missing part; a gap: "self-centered in opinion, with curious lacunae of astounding ignorance" (Frank Norris).
2. Anatomy A cavity, space, or depression, especially in a bone, containing cartilage or bone cells.
[Latin lacūna; see lagoon.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.