n. pl. so·ri (sôrī)
1. A cluster of sporangia borne on the underside of a fern frond. Also called fruit dot.
2. A reproductive structure in certain fungi and lichens.
[New Latin sōrus, from Greek sōros, heap; see teuə- in the Appendix of Indo-European roots.]
(click for a larger image)sorus
sori on the frond of
a polypody fern
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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:
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