Does a coin tossing algorithm terminate?
The formal, unambiguous way to state this is “terminates with probability 1” or “terminates almost surely”. In probability theory, “almost” means “with probability 1”.

For a probabilistic Turing machine, termination is defined as “terminates always” (i.e. whatever the random sequence is), not as “terminates with probability 1”. This definition makes decidability by a probabilistic Turing machine equivalent to decidability by a deterministic Turing machine supplied with an infinite tape of random bits — PTM are mostly interesting in complexity theory. In applied CS, though, computations that always give the correct result but terminate only with probability 1 are a lot more useful than computations that may return an incorrect result.