1.(used colloquially) having the relationship of friends or pals • Syn: matey, pally, palsy-walsy • Similar to: friendly • Derivationally related forms: mate (for: matey), chum, chumminess • Usage Domain: colloquialism 2.(used informally) associated on close terms - a close friend - the bartender was chummy with the regular customers - the two were thick as thieves for months • Syn: buddy-buddy, thick • Similar to: close • Derivationally related forms: chum, chumminess • Usage Domain: colloquialism