Is meaning without actually existing reference naturalizable?

According to Jerry Fodor, meaningful expressions denoting no actual entity, like “unicorn”, do not constitute an exception to his project of semantic naturalization based on the notion of asymmetrical dependence between causal relations. But Fodor does not give any principled reason in order to show that, say, a non- unicorn caused “unicorn”-token means UNICORN, as he on the contrary does regarding a non-X caused “X”-token for any actually existing X. Nevertheless, his claim that one such expression has a mere denotational meaning can be accounted for, though in a non-naturalistic way. Suffice it that one appeals to the weak Meinongianism contained in the thesis that one can directly refer to possible entities by means of a suitable fixing-reference description.