Equivalent of Ctrl-W for IntelliJ Mac

Select word: option+Up arrow

(IntelliJ IDEA 2016.2.3 on macOS Sierra 10.12)

It's called now Extend selection, as mentioned before by default AltUp.

IntelliJ IDEA 2019.1 (Ultimate Edition), Build #IU-191.6183.87
macOS Mojave 10.14.3

Depends on Preferences | Keymap. The action is called Select Word at Caret.

• Mac OS X keymap: CmdW (Cmd=Meta)
• Mac OS X 10.5+ keymap: AltUp (Alt=Option=⌥)