Light and lively discussion.
Talk about trivial or nonsensical matters; inconsequential or incessant conversation.
The chattering of teeth due to trembling, shivering, etc.
To talk trivially, nonsensically, or incessantly.
A personal relationship between two people.
Matching each member of one set with exactly one member of another set.
Injective, being an injection: having the property that no two elements of the domain are mapped to the same image.
Involving direct communication between two people.