What does bipedal mean?
"Bipedal" is an adjective describing animals that walk upright on two legs rather than four. It is most closely associated with humans — the only living primates that are habitually bipedal — but also applies to extinct hominins, certain dinosaurs such as Tyrannosaurus rex, and birds. Derived from Latin roots meaning "two feet," the word is standard vocabulary in anthropology, palaeontology, and zoology, where the evolution of bipedalism marks one of the defining transitions in human ancestry. Beyond strict biological usage, "bipedal" appears in discussions of robotics and anatomy, describing machines or stances modelled on the two-legged form. Its antonym is "quadrupedal," referring to four-legged locomotion. Because it is precise, technical, and widely understood, "bipedal" is a valuable word for anyone writing about evolution, animal movement, or the distinctive upright posture that sets humans apart from nearly every other mammal.
adjectiveUsing or moving on two feet; having two legs adapted for walking upright. In biology and anthropology, it describes animals (including humans) whose primary mode of locomotion is on two hind limbs.
- (Of an animal, especially a human) walking upright on two feet as the primary means of locomotion.
- (Of limbs or anatomy) adapted for or used in two-legged movement, as in 'bipedal stance' or 'bipedal locomotion'.
"Humans are the only fully bipedal primates, walking upright with an erect posture."
"The fossil footprints confirmed that the early hominin was fully bipedal."
"Tyrannosaurus rex was a massive bipedal predator, balanced by its long tail as it moved on two powerful hind legs."
Every step you take is a balancing act — humans are among the very few animals that walk entirely on two legs, a trait so rare that it essentially defines our species.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of bipedal
"Bipedal" derives from the Latin prefix bi-, meaning "two," combined with pes/pedis, meaning "foot," via the New Latin stem bipedalis. It entered English in the mid-19th century alongside the rise of comparative anatomy and evolutionary science. It shares its root with "biped" (a noun for a two-legged creature) and with a wider family of English words built on ped-, including "pedal," "centipede," and "impede."
Related word forms
How bipedal is actually used
"Bipedal" is primarily a scientific and formal term, common in anthropology, palaeontology, zoology, and biomechanics. It carries no strong connotation beyond its technical meaning. The adverb "bipedally" exists but is far less frequent than the adjective. It should not be confused with "biped", the noun referring to a two-legged animal itself.
Easily confused with bipedal
Quadrupedal describes movement on four feet, while bipedal describes movement on two.