Chummy (adjective)

1. Being on friendly terms; friendly and intimate.
2. Being on informal and friendly terms with someone.

Origin:

The word "chummy" is derived from the word "chum" meaning "friend". it is first recorded in english in the 19th century.

Examples:

1. They've been chummy since they were kids.
2. She's a bit too chummy for my taste.
3. The boss and the employee were chummy, often seen chatting and laughing together.
4. They became chummy after working on the project together.
5. We"re just chummy, we"re not actually friends.