-ic

-ic, -ical adjectives

1. There are three main situations:

(1) cases where only an adjective ending in -ic is available (e.g. alcoholic, basic, dramatic, linguistic, patriotic, public),

(2) cases where only an adjective ending in -ical is available (e.g. chemical, practical, radical), and

(3) cases where adjectives ending in -ic and -ical are available, often with a difference in meaning (e.g. classic / classical, comic / comical, economic / economical, historic / historical) but sometimes with no difference in meaning (e.g. geographic / geographical, problematic / problematical). Pairs that represent a difference in meaning are discussed as separate entries. When there is no difference in meaning, choice is often determined by considerations of idiom and sentence rhythm. Assertions relating to regional distinctions (e.g. that -ic forms are more common in AmE) lack adequate statistical support.

2. With one exception, all these adjectives, whether they end in -ic or -ical or both, form adverbs in -ically (basically, dramatically, geometrically, practically, etc.). The exception is public, which has an adverb form publicly.