Adjective
semi-decidable (not comparable)
(computing theory) Of a set, such that there is a deterministic algorithm such that (a) if an element is a member of the set, the algorithm halts with the result "positive", and (b) if an element is not a member of the set, (i) the algorithm does not halt, or (ii) if it does, then with the result "negative".
On the other hand, it is still semi-decidable, and a number of sound and complete calculi have been developed, enabling fully automated systems. Source: Internet
It is said that unification is semi-decidable for a theory, if a unification algorithm has been devised for it that terminates for any solvable input problem, but may keep searching forever for solutions of an unsolvable input problem. Source: Internet