Antonyms of adj narrow-mouthed

1 sense of narrow-mouthed

Sense 1
narrow-mouthed -- (having a narrow mouth)

INDIRECT (VIA narrow) -> wide, broad -- (having great (or a certain) extent from one side to the other; "wide roads"; "a wide necktie"; "wide margins"; "three feet wide"; "a river two miles broad"; "broad shoulders"; "a broad river")

Similarity of adj narrow-mouthed

1 sense of narrow-mouthed

Sense 1
narrow-mouthed -- (having a narrow mouth)
       => narrow (vs. wide) -- (not wide; "a narrow bridge"; "a narrow line across the page")