Comparative form of chummy: more chummy(adjective)
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Use "chummier" in a sentence
"I was wondering why they sometimes devs and journos are chummier than journos and, say, studio execs."
"Indeed, there is no one on Earth chummier with actual communists than Rupert Murdoch, owner of right-wing papers and channels."
"The old days were definitely chummier, but even now there are fora for author/reviewer friendships (conferences, publishers dinners, etc.) that encourage a let's-be-friends kind of relationship."