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word-forming element of Greek origin appended to nouns and denoting collective numerals (triad, Olympiad) and fem. patronymics (Dryad, Naiad, also, in plural, Pleiades, Hyades), thence also plant family names; from Greek -as (genitive -ados), fem. suffix equivalent to -is. From its use in Iliad (from Greek Ilias poiesis "poem of Ilion," that is, Troy) it has formed titles of poems in imitation of it (Columbiad, Dunciad.