My study guide/notes... my definitions may not be perfect, but they help me with concepts.
Service Set (SS) - all the devices connected to a wireless LAN.
Basis Service Set (BSS) - a single access point and all of its connected devices
Independent BSS / Ad Hoc / Peer-to-peer - devices talk to each other without a central authority like an access point
Infrastructure BSS - an access point that connects to a larger distribution network
Extended Service Set (ESS) - a collection of BSS that are working together to provide wireless service in an area
Basis Service Set Identification (BSSID) - the MAC address of the access point
Service Set Identifier (SSID) - the unique identifier for a BSS or ESS, what we commonly call the name of the wireless network