adjective, chum·mi·er, chum·mi·est. Informal.
Origin of chummy
Examples from the Web for chumminess
As her reception of Paul's sister was not conducive to chumminess, Paul did not bring Linda again.Big Timber|Bertrand W. Sinclair
Ive always wondered at your chumminess with him, said Nelson slowly, reseating himself.The New Boys at Oakdale|Morgan Scott
I will do my best to be a good wife to you—but chumminess is not mine to give, nor can I promise ever to be your dicky-bird.
He was a jolly man, given to oratory and to chumminess with the arts.Babbitt|Sinclair Lewis
That is due to the chumminess or the affinity of iron with oxygen.The Boy With the U.S. Miners|Francis Rolt-Wheeler