In the What is Random? vlog of the Vsauce channel, Michael says (start from 3:25):
In the 1300s, random meant running or at great speed. Later, it would be used to describe things that have no definite purpose. It wasn't until the 1800s that random took on a particular mathematical definition. Then in the 1970s, MIT's student paper popularised the use of the word random to simply mean strange.
So, it must after 1970s that the word "random" started to have the meaning as we know today. So before that, what word was used instead, both for mathematicians/scientists and normal people?
And why did the word "random" spread out, when there was already another exactly term for that?