biped

This term is primarily used in biological and zoological contexts to categorize organisms based on their locomotion. It carries a clinical, descriptive tone rather than a casual one, often appearing in scientific texts to distinguish humans and birds from quadrupeds.

While the word is technically a noun, it is frequently used as an attributive noun to modify other words, such as in the phrase "bipedal locomotion." This shift from the noun "biped" to the adjective "bipedal" is common when describing the mechanics of movement rather than the animal itself.