A friend of mine asked me this question but I couldn't answer it. I have tried to find an opposite (not exactly though) of buck(ed) teeth which means:

Large front teeth protruding over the others; the phrase may come from buck, the adult male of some animals, such as rabbits—which have this type of front teeth.

[Farlex Trivia Dictionary]

What is the word or phrase that describes a person's teeth whose bottom teeth protrude over their upper teeth? I couldn't find any image because I don't know the term. Instead, I attach a below picture which shows a typical buck(ed) teeth (a bit exaggerated).

Child with buck teeth

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    Not the same thing as buck teeth, perhaps, but buck teeth are often associated with an overbite. The opposite of that is an underbite. – Drew Feb 29 '16 at 16:25
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    see also snaggletooth – Mitch Feb 29 '16 at 16:39
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    This link describes protruding (aka flaring) teeth as:“lower & upper jaw growing at different rates; forward or outwardly tilted front teeth, can also be known as “buck teeth”,” BUT it doesn’t discuss the opposite. A multi-word description of the opposite condition could be “backward or inwardly tilted front teeth,” but I can’t find a suitable one-word antonym for “protruding” (or “flaring”) that wouldn’t be confusing (like “caved-in/receding” teeth). For a phrase maybe “inward[ly] tilting teeth” or “inturned [upper front] teeth”? – Papa Poule Feb 29 '16 at 18:20
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    Here’s some before/after photos of the tooth placement that I think you’re describing (regardless, I find her pretty both before and after). – Papa Poule Feb 29 '16 at 18:40
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    One user suggests that the opposite of buck teeth must be teeth that incline backwards, meanwhile two users have interpreted it as the lower set of teeth protruding over the upper set. Are you interested in both terms, or has @drew has interpreted your question correctly ? – Mari-Lou A Feb 29 '16 at 21:59

That would be called an underbite.

underbite un·der·bite (ŭn'dər-bīt')

n. Malocclusion in which the lower teeth overlap the upper teeth.


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    Not really. See my comment to the question. Buck teeth is not quite the same thing as overbite. Buck teeth can involve only one or a few teeth. The opposite would be at least one tooth protruding backward, not forward. – Drew Feb 29 '16 at 16:29
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    @Drew Right, it's an answer to "bottom teeth protrude over their upper teeth" not to "opposite to buck teeth". They're separate questions, I guess. – Spehro Pefhany Feb 29 '16 at 16:31

I think you are referring to prognathism :

  • Having jaws or mouthparts that project forward to a marked degree.

enter image description here

  • That's underbite. See my comment to the question. Overbite is not quite the same thing as buck teeth (which can be only one or a few teeth). – Drew Feb 29 '16 at 16:27

You might consider, bulldog teeth.

This is commonly stigmatized as "bulldog teeth." Underbites are typically caused by missing upper teeth. invisalignbrickell.com

Whether you are born with, or develop, an overbite (aka “buck teeth”), an underbite (also known as “bulldog teeth”), a crossbite (upper teeth don’t come down in front of lowers when biting normally), an open bite (space between uppers and lowers when back teeth bite down together), a misplaced midline (the center of your upper fronts don’t line up with the center of your lower fronts), or have spaces or crowding, there are various types of orthodontic appliances that can address each issue. Drews Dental Clinic


The opposite of protruded teeth is retruded teeth

enter image description here

Patient Treatment Case 2: Deep bite, retruded teeth.

This teenage patient had upper front teeth that were tipped backwards and a very deep bite. With braces we were able to improve the bite and tooth position, which also improved the appearance of the gums.

  • +1 That's certainly what I'll call such teeth from now on! – Papa Poule Mar 1 '16 at 0:15

Your titular query would leave room for misinterpretation, were it not for the remainder of your question,

What is the word or phrase that describes a person's teeth whose bottom teeth protrude over their upper teeth?

The "word or phrase" most familiar to me, describing that phenomenon, is

undershot, adj. (and n.)
2. Having the lower jaw or teeth projecting beyond the upper; underhung.

["ˈundershot, adj. (and n.)". OED Online. December 2015. Oxford University Press. http://www.oed.com/view/Entry/212031?redirectedFrom=undershot (accessed March 01, 2016).]

'Undershot' may or may not be more precisely descriptive, depending on the context, if it is used as an adjective along with the relevant defining noun, as in

undershot tooth or undershot teeth

You asked about people, so I'll limit myself to a couple of images of people with undershot teeth produced by an online search (Ecosia):

undershot1enter image description here

The condition, however, seems to be much more common among dogs and rodents.

While 'underhung', as suggested by the OED Online definition of 'undershot', might seem at first blush to be a more or less exact synonym of 'undershot', it is only an adjective (disregarding colloquial and disparaging uses related to other parts of the anatomy). Further, the definition of 'underhung' suggests a condition of the jaw, rather than a condition of both the jaw and the teeth (etc.):

underhung, adj.
a. Having the lower jaw projecting beyond the upper, or coming unusually far forward.
b. Projecting beyond the upper jaw.

There appears to be controversy regarding 'buck teeth' (also 'bucktooth' or 'bucktoothed'). Various lexicographers admit a shade or two of disagreement: American Heritage and Collins specify that 'bucktooth' applies only to upper front teeth; Random House Kernerman Webster's uses especially to relate 'bucktooth' to upper teeth, while not ruling out projecting lower teeth; OED Online doesn't weigh in to favor either upper or lower.

  • Thank you for your answer. Please go ahead and edit the question. – user140086 Mar 1 '16 at 6:10
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    Downvote is a joke. I don't take it seriously. This question started with heavy downvotes, but see how many upvotes it generated 3 months later. I thought about titling the question "opposite of overbite", but it is too easy to get "underbite". – user140086 Mar 1 '16 at 6:20
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    Exactly. It's the real fun part of ELU. Some think they can make a difference with voting, but hell no. Then, why do I downvote? I think I can make a difference. Thus, I rarely downvote. – user140086 Mar 1 '16 at 6:31

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