Learner's definition of LESSON
an activity that you do in order to learn something
something that is taught
a single class or part of a course of instruction
something learned through experience
see also object lesson
political leaders who have failed to learn the lessons of history
I've learned my lesson —I'll never do that again!
We learned our lesson the hard way. [=we learned from an unpleasant experience]
I'm glad they got caught. That will teach them a lesson! [=they will learn that they should not do that again]
Let that be a lesson to you —if you don't take better care of your toys they'll get broken!
a part of the Bible read as part of a church service