-ical
adjective suffix
: -ic
symmetrical
geological
—sometimes differing from -ic in that adjectives formed with -ical have a wider or more transferred semantic range than corresponding adjectives in -ic 
Word History
Etymology
Middle English, from Late Latin -icalis (as in clericalis clerical, radicalis radical)
Kids Definition
-ical
adjective suffix
i-kəl
: -ic
symmetrical