General:
* Chat
* Converse
* Talk
* Speak
* Discuss
* Gab
* Shoot the breeze
* Have a chinwag (British)
* Mingle
* Socialize
More Casual:
* Jaw
* Yak
* Blab
* Gossip
* Spill the beans
* Hang out
* Kick back
* Catch up
* Shoot the bull
Informal & Lighthearted:
* Chit-chat
* Small talk
* Make conversation
* Have a natter (British)
* Banter
* Rag (tease playfully)
More Slangy/Informal:
* Rap
* Spit
* Whine
* Rave
* Yell (can be more forceful)
* Rant (can be more negative)
* Moan
The best word to use depends on the specific context and tone you want to convey.
For example:
* "We chatted for a while about our plans for the weekend." (casual but friendly)
* "They were just yakking away, I couldn't hear myself think." (informal and slightly negative)
* "Let's hang out and shoot the breeze." (very casual and friendly)
* "She was ranting about the traffic." (informal and negative)