Possible Duplicate:
Why is it “geometric” but “theoretical”?
“Ironic” vs. “ironical”
“Comic” vs. “comical”
“Historic” vs. “historical”
What's the difference for instance between ironic/ironical, rhythmic/rhythmical, historic/historical, comic/comical, economic/economical? If these adjectives are identical in meaning why the need for the different endings?
