Leaving aside the obvious issue that an old abridged dictionary probably isn't the best place to look up mathematical terminology, what does 'stochastic' actually mean - and how does it differ from 'random'? 1/ 
The two words are often used interchangeably, but there is a subtle difference. Think about a coin toss. If you flip a coin, the outcome is a *random* event - you have no idea if it will land heads or tails... 2/
But suppose you flip a coin a few times and record the outcomes - you'll start to notice predictable features in the data. The coin flips are a *stochastic process*, and we can analyse them statistically (e.g. total number of heads/tails will follow binomial distribution) 3/
Going back to viruses, individual transmission events involve randomness, but the distribution of these events can be described statistically by treating them as a stochastic process nature.com/articles/natur… 4/
As an aside, the quirks of coin tossing and games of chance have been hugely influential on the development of maths and stats - as I wrote about a few years ago: theguardian.com/science/alexs-… 5/5
