interjection. Used to express doubt or disapproval
the GNU version of the Collaborative International Dictionary of English
interjection. An exclamation denoting surprise, or contempt, doubt, etc.
The Century Dictionary and Cyclopedia
An exclamation uttered in the manner of a grunt, and expressive of disbelief, doubt, or dissatisfaction.
To utter the syllable humph, as in dissatisfaction; mutter; grumble.
Word Usage
"I am not well assured whether an attack of the "humph" -- "the humph which is black and blue" -- is not also diagnosed by the contemplative insects and forthwith attended to."