Isn't this traditionally called promiscuous mode?
Monitor mode is a level higher, and allows for capturing all wireless frames regardless of what SSID they are for, and regardless of whether they contain IP packets or are just signaling like beacon and connection requests.
> Unlike promiscuous mode, which is also used for packet sniffing, monitor mode allows packets to be captured without having to associate with an access point or ad hoc network first. Monitor mode only applies to wireless networks, while promiscuous mode can be used on both wired and wireless networks.