tickseed n any of numerous plants of the genus Coreopsis having a profusion of showy usually yellow daisylike flowers over long periods; North and South America Usage(s) tickseed sunflower, Jerusalem artichoke, sneezeweed, swollen bladderwort, clammy ground cherry, purslane, muskflower, rough-fruited cinquefoil, climbing boneset,. Synonym(s) coreopsis tickweed tick-weed