Phatic

From Word-a-day:

phatic (FAT-ik) adjective

   Relating to a communication meant to generate an atmosphere of
   social relationship rather than to convey some information.

[Coined by anthropologist Bronislaw Malinowski (1884-1942). From Greek phatos, from phanai (to speak), which also gave us prophet and aphasia (loss of ability to understand language as a result of an injury).]

When you bump into your neighbor on your way out and say, "How are ya?"
you're engaging in phatic communion. The idea is not to inquire your neighbor's state of affairs but simply to create a feeling of shared goodwill.