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les·son (lĕsən)
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n.
1. Something to be learned: lessons from observing nature.
2.
a. A period of instruction; a class.
b. An assignment or exercise in which something is to be learned.
c. The act or an instance of instructing; teaching.
3.
a. An experience, example, or observation that imparts new knowledge or understanding: The conversation was a lesson in tact.
b. The knowledge or wisdom so acquired. Missing the opening act taught me a lesson about being late.
4. often Lesson A reading from the Bible or other sacred text as part of a religious service.
tr.v. les·soned, les·son·ing, les·sons
Archaic
1. To teach a lesson to; instruct.
2. To rebuke or reprimand.

[Middle English lessoun, from Old French leson, from Latin lēctiō, lēctiōn-, a reading, from lēctus, past participle of legere, to read; see leg- in the Appendix of Indo-European roots.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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