The Modern English adjectival suffix -ic was first seen as a suffix in English during the Middle English period. It was borrowed in words from Old French '-ique', which came from Latin '-icus', which came ultimately from Ancient Greek '-ικοσ (-ikos)'. There are some that contend that '-icus' was native to Latin and was cognate with rather than borrowed from Greek. At any rate, the suffix -icus was very wide-spread by the Classical Latin period in native words as well as in words derived from Greek.
It is also used in chemistry to denote certain chemical compounds in which a specified chemical element has a higher oxidation number than in the equivalent compound whose name ends in the suffix -ous. See Inorganic nomenclature.