n. pl. plan·u·lae (-lē′)
The flat, free-swimming, ciliated larva of a cnidarian.
[New Latin plānula, from Latin, feminine diminutive of plānus, flat (from its shape); see pelə-2 in the Appendix of Indo-European roots.]
planu·lar, planu·late′ (-lāt′) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.