Synonyms for Counterfactual:

adj.

counter to facts (adjective)
untruthful, false, untrue, Truthless, wrong.
dishonest (adjective)
untrue.
false (adjective)
untruthful, contrary to fact.

n.

false, untruthful, specious, Truthless, true, wrong, untrue, spurious. counterfactual (noun)
conditional, contrary to fact.

Other synonyms:

untruthful, Truthless, untrue. specious. spurious, wrong, false. Other relevant words:
false, untruthful, specious, Truthless, true, wrong, untrue, spurious.