Score (n.)(v.) - Who's keeping score?
The number of points earned in a game, or a rating of performance in an activity.
It can also refer to a mark, incision, a debt owed to someone, or even the number twenty.
To mark or scratch something, usually to keep track of a number, and can refer to the act of keeping track of numbers.
History & Etymology
Vigesimal, That’s a fancy way of saying counting by twenties. Just like how we use a base ten system, the Celts and even the early french and english for a while used a vigesimal system for counting large numbers. This was an easy for people like shepards to keep track of things like sheep. For every twenty sheep they counted they would mark, or score, a piece of wood, and this is actually the ultimate origin of all the many definitions of the word score.
The PIE word sker- already meant to cut, and by the time of the development of Proto-Germanic it already had the meaning of twenty as well as to cut.
When Abraham Lincoln said, “Four score and seven years ago,”in his historic Gettysburg address he wasn’t only making his speech more flowery than just saying “87 years ago,” he was trying to evoke history, an older way of speaking. To be more specific he may have been referring to a passage from the book of Psalms from the Bible, in the KJV it’s translated as, “The days of our years are three score years and ten,” basically it’s stating that the human lifespan is around 70 years. Lincoln was most likely trying to point out the nation was now older than most of the people living in it. Even at that time this nation had a real history.