Synonyms/Hypernyms (Ordered by Estimated Frequency) of verb dumbfound

1 sense of dumbfound

Sense 1
perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfound -- (be a mystery or bewildering to; "This beats me!"; "Got me--I don't know the answer!"; "a vexing problem"; "This question really stuck me")
       => confuse, throw, fox, befuddle, fuddle, bedevil, confound, discombobulate -- (be confusing or perplexing to; cause to be unable to think clearly; "These questions confuse even the experts"; "This question completely threw me"; "This question befuddled even the teacher")

Antonyms of adj dumbfounding

1 sense of dumbfounding

Sense 1
astounding, dumbfounding, dumfounding -- (bewildering or striking dumb with wonder)

INDIRECT (VIA incredible) -> credible, believable -- (capable of being believed; "completely credible testimony"; "credible information")

Similarity of adj dumbfounding

1 sense of dumbfounding

Sense 1
astounding, dumbfounding, dumfounding -- (bewildering or striking dumb with wonder)
       => incredible (vs. credible), unbelievable -- (beyond belief or understanding; "at incredible speed"; "the book's plot is simply incredible")