I wanted to write about intense fear, something like abject terror, but implying that it strikes you dumb with fear. Am I missing something obvious, or should I just settle for changing the wording to avoid the problem?
There is exactly such a word:
so shocked or surprised as to be unable to speak: he was dumbstruck with terror.
Are you looking for stupefying?
I can think of stunning, paralysing, shocking, staggering, traumatising, devastating, demolishing, overwhelming, shattering, ravaging terror.
Another option I thought of today was aphonic, but I think that is a tad too esoteric, and more likely just to trip readers up.
In the end, I think the solution was staring me in the face:
abject, speechless terror
What about "I was rendered speechless"? It might be so common that it's more of a cliche.
“nonplus” answers the broad question posed by your title.