Synonyms:
chummy, buddy-buddy, thick(p)
Meaning: (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"
Synonyms:
chummy, matey, pally, palsy-walsy
Meaning: (used colloquially) having the relationship of friends or pals
Usage examples
For some time before that game you and Grant were very chummy; you were nearly always together, so that everybody noticed it.