[maweki]

In logic programming monotonic means that adding a fact or rule does not remove an answer.

Like SQL has monotonic queries where adding entries to a relation never gives you fewer answers.

More formally: Database1 subset Database2 implies Query(Database1) subset Query(Database2) for all databases

Which is exactly the definition of monotonicity (x =< y implies f(x) =< f(y)) applied to sets and functions on sets.

[javajosh]

I guess that makes sense. I wonder though what other adjectives might apply to a "language core" other than "monotonic"? Why did you pick that one? Also are there any language are are monotonically decreasing? This is less useless than it sounds, since this is an elegant way to model decay, and decay is hard to model.