"by the hundred;" with a preceding numeral expressing a proportion of the whole amount, 1560s, per cent, from Modern Latin per centum "by the hundred" (see per and see hundred). Until early 20c. often treated as an abbreviation and punctuated accordingly.
word-forming element in nouns of act, process, function, condition, from Old French and French -age, from Late Latin -aticum "belonging to, related to," originally neuter adjectival suffix, from PIE *-at- (source of Latin -atus, past participle suffix of verbs of the first conjugation) + *-(i)ko-, secondary suffix forming adjectives (see -ic).
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Definitions of percentage
a proportion in relation to a whole (which is usually the amount per hundred);