What does thirty mean?
“Thirty” is the cardinal number 30, the sum of twenty and ten or three tens. It is used when counting objects, reporting a score, stating a duration or age, or identifying a numbered group. As an age, “thirty” normally denotes the exact age, whereas “in one's thirties” covers the decade from 30 through 39. In measurements, it behaves like any other number: “thirty minutes” or “thirty degrees.” Its meaning and usage are the same in standard British and American English, and its register is neutral, ranging from formal reports to everyday conversation. The related plural noun “thirties” commonly names the decade of a person's life and can also refer to a score or group of thirty, as in “a score in the thirties.” The word is useful because it illustrates how English combines an exact numerical value with contextual meanings such as age, time, and range, while its historical connection to “three” is reflected in related forms such as “third” and “thirteen.”
The cardinal number equivalent to three tens, used to count objects, measure quantities or durations, state an age, or report a score.
"The workshop will begin in thirty minutes."
A score, total, or quantity of thirty, especially a score of 30 points or marks.
"Her highest score was a thirty."
The plural form “thirties” can denote the decade from 30 to 39, as in 'in his thirties,' or a score or quantity in the range of 30 to 39.
The plural most commonly denotes the decade from 30 to 39 and may also refer to scores, quantities, or groups within that range.
"She is in her thirties."
Thirty is XXX in Roman numerals: three Xs, each worth ten.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does thirty come from?
The word descends from Old English þrītig, which was inherited from Proto-Germanic and used for the cardinal number 30. Its root comes from the same Indo-European numeral root represented by English “three,” with which it is also cognate with “third” and “thirteen”; related forms such as “thrice” preserve the same numerical root. The inherited Germanic form developed into modern English “thirty” without altering its established numerical value.
Related word forms
How thirty is actually used
The word is neutral in register and standard in both British and American English. When it quantifies people, normal plural agreement applies: 'Thirty people are arriving,' although 'Thirty is enough' is also common. 'In one's thirties' denotes the decade from 30 to 39.
Easily confused with thirty
Thirteen means 13, whereas thirty means 30.