When the word end is used as a verb, it means to finish or terminate something. If you put an end to something, you have stopped it from happening.
The baseball game ended after Johnnie hit the ball through Old Man Peterson's window. Boy, was he angry! He came running out of his house, waving his arms and yelling!
Mrs. Marzullo had seen more than one of her students copying homework, but when she saw Margie, her prize pupil, copying, she knew that she needed to put an end to it, once and for all.
As a noun, end means the final point of something. Many idioms use this meaning, including dead end, which is a road that ends without an outlet, and come to a sticky end, meaning dying or losing in an unpleasant way.
We had reached the end of the road. The road simply stopped, and beyond were trees and a few hills. It was a dead end, although there had been no sign to warn us as there usually would be.
The character of Nils comes to a sticky end about halfway through the film, although I don't want to tell you too much and spoil it for you.
To terminate is to bring to an end, particularly when something is incomplete. In the world of work, terminating someone is firing them. In general, termination carries the sense of something ending before it is supposed to.
Because of consistent absences and late arrivals, Mr. Marks decided to terminate Jonas' employment this morning. Jonas won't find out until tomorrow, as he called in sick today, for the fourth time this month.
Unhappy with how things were going, Becky decided to terminate her engagement to Steve and go back to Chris, her first and best love. Hopefully, Chris felt the same way.
Two colorful expressions that are synonymous with terminate, in the sense of firing from a job, are gave him the axe and cut him loose.
Apparently, the boss had had enough of Mark's poor customer service. There had simply been too many complaints. So, he decided to give Mark the axe.
Even after more than fifteen years with the company, the minute that Sarah's sales numbers fell, they cut her loose. Now she's looking for a job and thinking about a career change.