adj

• (zoology) Having only two teeth.
• (phonetics) articulated with both the upper and lower teeth.
  "Finally, a position of almost bidental contact can be a paralinguistic voice qualifier or secondary articulation we should acknowledge as a dentalization, that is, the articulation of vowels and consonants 'through one's teeth', which can make the labial kinesic component of normal articulation be still present and vary from lip rounding or protrusion with close front vowels to horizontal distension with close back vowels."

noun

• (zoology) An organism that has only two teeth, especially a dinosaur of the infraorder Dicynodontia.
  "The letter proceeds to state that, besides this monster, there is a great variety of remains of another new order of animals, which Mr. Bain has deginated as bidentals, from their possessing only two teeth, or rather tusks, in the upper jaw, and none whatever in the lower jaw."

noun

• (historical) In Ancient Rome, a place that had been struck by lightning and consecrated and enclosed.
  "The bidental was a place that had been struck with lightning, and afterwards expiated by the erection of an altar and the sacrifice of sheep, hostiis bidentibus; from which last circumstance it took its name."