To indicate a soft o.Unstoppable (Why is there a second P in that word?)
In case you forget to say, or write, the first P...Unstoppable (Why is there a second P in that word?)
Unstopable would presumably refer to an ore body that cannot safely be stoped, perhaps due to instability of the surrounding rock.To indicate a soft o.Unstoppable (Why is there a second P in that word?)
Single p would make a hard o - like the difference between sloping and slopping.
You can thank me later.
/pedant