Zero (2)
Zero in on
- Direct or focus attention on
- Head for, move towards
Zero out
- Cut off funding for a project
- Reduce to zero, cancel, remove

Zip (3)
Zip around
- Move quickly
Zip by
- Pass quickly
Zip up
- Keep quiet

Zone (3)
Zone in
- Pay attention after not doing so
Zone in on
- Pay attention after not doing so
Zone out
- Not pay attention
- Dissociate yourself from a situation

Zonk (1)
Zonk out
- Fall asleep

Zoom (4)
Zoom in
- Focus more closely
Zoom in on
- Focus more closely
Zoom off
- Go somewhere quickly
Zoom out
- Focus less closely