a.k.a. tethered, untethered
To use a smartphone in order to connect a computer or another device to the Internet. This term has morphed to refer to the neediness one has for one's smartphone and how often you need to check it, as in "OMG we couldn't even enjoy dinner last night cuz she was so tethered to her phone."

Untethered in modern slang refers to not needing your phone, or worse yet, to a device like an Apple Watch because "that's one way you can be untethered from your phone."
See also : yetties  EAPFS  
NetLingo Classification: Online Jargon