Adjectives Ending With -ic and -ical

No rule can be given for the formation of adjectives with -ic and -ical. In certain cases -ic words are preferred over their -ical counterparts and in other cases, -ical words are preferred. A number of -ic and -ical pairs have differentiated themselves over time and now have distinct meanings.

Today the pair botanical is more common than botanic. Metaphorical is used more than metaphoric, but ironic and problematic are more common than their counterparts ironical and problematical. The word polemic is a noun and polemical is an adjective.

The word pairs classic/classical, comic/comical, economic/economical, electric/electrical, historic/historical and periodic/periodical have different meanings. The word classical is often used for well-defined historical periods of culture and science as in classical music. The word classic has a broader meaning. It has the meaning of great significance as in classic literature. The word comic relates to comedy and comical has the meaning of funny. The adjective economical relates to the economy and economics while economic means thrifty. The word electrical relates to electricity, for example, electrical outlets. Devices that run on electricity are electric such as electric cars and electric heaters. The word historical relates to the past as in a historical document. However, historic means historically signficiant as in a historic battle. The adjective periodic is used for situations that take place at regular intervals or are intermittent. The word periodical has a narrower meaning and means published at regular intervals.

In many cases adjectives with -ic and -ical are interchangeable as in botanic/botanical and ironic/ironical. Though these word pairs are identical in meaning, one of the two pairs is often more common than the other. With certain words pairs such as economic/economical and historic/historic, they were once identical but now have different meanings.