What does zeroth mean?
“Zeroth” is an ordinal adjective meaning “number zero” or “immediately before first” in a sequence. It is especially common in mathematics and the physical sciences, where terms such as “zeroth law,” “zeroth order,” and “zeroth approximation” identify a starting level or a position preceding the first. In broader formal use, it can describe the lowest or initial rank in a hierarchy, as in “zeroth priority.” The word is useful because it distinguishes an ordinal position from the numeral “zero”: zero names the value itself, while zeroth identifies its place in an ordered system. Although its technical use is well established, “zeroth” is less common in everyday conversation, where speakers may simply say “zero.” Its clearest application is in systems that need to label an initial or foundational stage before ordinary first, second, and subsequent positions begin.
adjectiveAn ordinal adjective denoting the position immediately before the first, or the item numbered 0, in a sequence. It is especially used in mathematics, formal numbering systems, and technical contexts.
- Denoting the position or item immediately before the first in an ordered sequence.
- Denoting the lowest rank or initial status in a hierarchy, especially when the starting point of that hierarchy is being treated as a formal level.
"The zeroth approximation provides a starting point for the more accurate calculations that follow."
"The zeroth law of thermodynamics describes the equilibrium state of an isolated system."
"This is only the zeroth draft, but it gives us a useful framework for the final version."
Zeroth is a mathematical way of saying “before first” without pretending that every sequence begins with the first place.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does zeroth come from?
“Zeroth” was formed in the 19th century by adding the ordinal suffix “-th” to “zero,” following the pattern of other ordinal forms. “Zero” itself entered English through Medieval Latin and ultimately derives from the Arabic ṣifr, meaning emptiness or a zero count. “Cipher” and “cypher,” which are also associated with the same Arabic-derived tradition of zero and calculation, provide related historical cognates.
How zeroth is actually used
“Zeroth” is chiefly formal and technical. It is most common in mathematics, physics, ordered classifications, and technical documentation, while everyday speakers usually use “zero” when referring to the first position in a sequence.
Easily confused with zeroth
“Zero” is the numeral or numerical value 0, whereas “zeroth” is an ordinal adjective identifying the position or item numbered 0.