widemouthed

[wahyd-mouth d, -moutht]

adjective

(of a person, object, body of water, etc.) having a mouth that is wide: a widemouthed river.
(of a person) having the mouth opened wide, as in astonishment or horror.

Origin of widemouthed

First recorded in 1585–95; wide + mouth + -ed³

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Even Lauzanne seemed lifted out of his usual lethargy, and, widemouthed, was pulling Allis out of the saddle.
Thoroughbreds
W. A. Fraser
The crouching giant looked up at him with a widemouthed grin.
In the Morning of Time
Charles G. D. Roberts
If the "hpurui, water jug" was handled, it would show that handled jugs were called by the same name as widemouthed jars, hpurui.
Mohave Pottery
Alfred L. Kroeber