un-
ʌn
un- is a hand turning backwards, not just a 'no'
The picture A hand turns something the other way and pulls it out, leaving the slot sitting empty. un- unties what was done and leaves it undone; re- goes back to the start and runs again.
Where the picture shows up in un-
-
turning a lock the other way
Please unlock the back door.
pliːz ʌnˈlɑːk ðə bæk dɔːr
Open the back door for me, please.
The key turns the opposite way from locking and the bolt slides free.
It runs the lock action backwards.
-
pulling out what was pushed in
Can you unplug the printer?
kæn juː ʌnˈplʌɡ ðə ˈprɪntər
Take the printer cord out of the socket.
The plug sitting in the wall is pulled and comes out of the holes.
-
what should be there is gone
The machine is unsafe without the guard.
ðə məˈʃiːn ɪz ʌnˈseɪf wɪˈðaʊt ðə ɡɑːrd
That machine is dangerous with the guard off.
The guard has been lifted off the machine and the blade stands bare.
safe with the safety taken out of it.
-
not done yet
Two boxes are still unopened.
tuː ˈbɑːksɪz ɑːr stɪl ʌnˈoʊpənd
Two of the boxes have not been opened.
Two boxes stacked in the corner, tape still unbroken across the top.
-
no way to do it at all
His handwriting is unreadable.
hɪz ˈhændraɪtɪŋ ɪz ʌnˈriːdəbəl
Nobody can read his writing.
You lean in close and the lines stay tangled; they never resolve into letters.
un- in front of -able closes the road off.
All of it in one picture
un- is one hand working backwards. Turn the bolt the opposite way and you unlock; pull the plug out of the socket and you unplug. Once that hand has passed, the empty slot is the meaning all by itself: the guard is gone, so the machine is unsafe; the tape is still on, so the boxes are unopened; there is no road from the line to a letter, so the writing is unreadable. With any un- word, just look for what was pulled out or what is missing.