What does cubit mean?
The cubit was an ancient unit of linear measurement derived directly from the human body — the distance from the elbow to the tip of the middle finger, conventionally taken as about 18 inches or 45 centimetres. It served as one of the earliest standardised measures across the ancient Near East, Egypt, Greece, and Rome, though its exact length varied from culture to culture and even within them; the Egyptian 'royal cubit', used for monumental construction such as the pyramids, measured closer to 20.6 inches. Today the word appears chiefly in biblical translation, archaeology, and historical writing, where it lends texts an appropriately archaic flavour — most famously in the description of Noah's Ark as three hundred cubits long. Because the cubit was never truly uniform, careful writers note which standard applies when quoting ancient measurements.
nounAn ancient unit of linear measure, roughly the distance from the elbow to the tip of the middle finger, typically reckoned as about 18 inches (45 cm), though it varied across cultures and eras.
- An ancient unit of length equal to roughly 18 inches (about 45 cm), originally based on the length of the human forearm from elbow to fingertip.
- The forearm itself, as anatomically understood (an older, largely obsolete sense).
"The ark in Genesis was said to be three hundred cubits long."
"Archaeologists estimated that the temple's doorway stood some twelve cubits tall."
"The builders marked out the foundation using a rod of one royal cubit."
Standard pluralisation; used freely when giving measurements in cubits.
"The stone walls rose forty cubits above the plain."
Egyptian 'royal cubits' were carved from granite and kept in temples as official standards — the ancient world's equivalent of a national bureau of weights and measures.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cubit
The word cubit comes from the Latin cubitum, meaning 'elbow' (literally 'the bending part'), which in turn derives from the verb cubare, 'to lie down'. It entered English via Old French in the medieval period, replacing native terms for the same measure. The Latin root cub- also produced words such as incumbent, recumbent, concubine, and succumb, all connected to lying or leaning.
Related word forms
How cubit is actually used
Cubit is almost exclusively encountered in historical, biblical, archaeological, and scholarly contexts; modern measurement uses metric or imperial units instead. Because actual cubit lengths varied widely between cultures (roughly 17 to 21 inches), writers citing cubit-based dimensions should specify which standard is meant when precision matters.
Easily confused with cubit
A qubit is a quantum bit, the basic unit of information in quantum computing, whereas a cubit is an ancient unit of length based on the forearm.
A cube is a three-dimensional solid shape or its cubic measure, while a cubit is a historical unit of length.