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a group of postage stamps having a common theme or a group of coins or currency selected as a group for study or collection; "the Post Office issued a series commemorating famous American entertainers"; "his coin collection included the complete series of Indian-head pennies"
an open clash between two opposing groups (or individuals); "the harder the conflict the more glorious the triumph"--Thomas Paine; "police tried to control the battle between the pro- and anti-abortion mobs"
a hostile meeting of opposing military forces in the course of a war; "Grant won a decisive victory in the battle of Chickamauga"; "he lost his romantic ideas about war when he got into a real engagement"