les·son 
/ˈlɛsn̩/ noun
plural les·sons /ˈlɛsn̩/ noun [count] 1 a : an activity that you do in order to learn something
▪ You can't go out to play until you've finished your lessons. ; also : something that is taught
▪ They studied the lessons [=teachings] of the great philosophers.
b : a single class or part of a course of instruction
▪ The book is divided into 12 lessons. ▪ Lesson 1: Introduction ▪ She took/gave piano lessons for years. 2 : something learned through experience
▪ 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! — see also object lesson 3 : a part of the Bible read as part of a church service
▪ You can't go out to play until you've finished your lessons. ; also : something that is taught
▪ They studied the lessons [=teachings] of the great philosophers.
b : a single class or part of a course of instruction
▪ The book is divided into 12 lessons. ▪ Lesson 1: Introduction ▪ She took/gave piano lessons for years.
▪ 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! — see also object lesson
