IPA: /ʌnˈwɒtʃəbl/
KK: /ʌnˈwɑːtʃəbl/
Something that is so bad or uninteresting that you cannot watch it.
The movie was so poorly made that it was completely unwatchable.
Unwatchable → It is formed from "un-" (meaning not) and "watch" (from Old English *wæccan*, meaning to be awake or to observe) and "-able" (meaning capable of). The word "unwatchable" means not capable of being observed or viewed due to poor quality or other reasons.
Think of 'not' ('un-') being able to 'observe' ('watch') something — that's why unwatchable means something you cannot watch.