Indefinite Meaning: Definition, Examples and How to Use It

Indefinite means not definite — not exact, not clearly fixed, or without a set limit. When plans are indefinite, nobody has pinned down the details; when an answer is indefinite, it is vague rather than precise; when a period of time is indefinite, no end date has been set. It is an adjective with three main uses in modern English: describing something unclear, describing something with no fixed limit, and — in grammar — labelling words like the articles a and an that point to something not specifically identified. This article gives the dictionary definition, the British and American pronunciations, the word’s history, the grammar connection, real examples, and answers to the questions people actually ask.

What does “indefinite” mean? The dictionary definition

The dictionaries are in close agreement, and Merriam-Webster’s three-part entry is the clearest map of the word’s territory:

• Not precise; vague. “An indefinite answer” — one that hedges, dodges, or refuses to commit. Cambridge’s wording is “not exact, not clear.”
• Having no exact limits. “An indefinite period of time,” “put on indefinite hold.” The end is not fixed — it may come, but nobody has named it.
• Grammar: designating an unidentified, generic, or unfamiliar person or thing. The indefinite articles a and an; indefinite pronouns. Here indefinite means “not pinned down to a particular one.”

Collins (Random House) phrases the same ground slightly differently: “having no fixed or specified limit” (an indefinite number), “not clearly defined or determined” (an indefinite boundary), and “not firmly decided or committed; uncertain; vague.” Notice the pattern: every sense is built from in- (not) + definite. The word’s whole job is to say that something definite is missing — a limit, a boundary, a decision, or an identity.

The related forms are indefinitely (adverb: “the meeting was postponed indefinitely”) and indefiniteness (noun), both recorded by Merriam-Webster.

Pronunciation

Four syllables, with the stress on the second:

• UK: /ɪnˈdef.ɪ.nət/ — “in-DEF-ih-nuht”
• US: /ɪnˈdef.ən.ət/ — “in-DEF-uh-nuht”

The difference between the two is small — the unstressed vowels reduce slightly differently — and either will be understood everywhere. The spelling trap is the ending: it is -ite, exactly like definite. “Indefinate” is a misspelling, one of the most common ones for this word, because the unstressed final syllable sounds like “-uht” in both varieties.

Where does “indefinite” come from?

The word entered English in the early 1500s (dictionaries date it 1520–30) from the Latin indēfīnītus — in- (“not”) + dēfīnītus (“definite,” from dēfīnīre, “to mark out the boundaries of”). So the literal history of the word is “not marked out”: no boundary drawn, no line fixed. That is still exactly what it means. The Latin root is also why the spelling is in-def-in-ite and not “indefinate” — it inherits the -ite of definite.

The grammar connection: indefinite articles and indefinite pronouns

Most people meet indefinite first in grammar class, and the grammatical use is the word’s third dictionary sense:

• Indefinite articles are a and an. They introduce a noun that is not already identified: “I saw a dog in the park” means some dog, not a particular dog we both know. The moment the dog is identified, English switches to the definite article the: “The dog was barking.” Collins’s Webster’s New World entry states it plainly: “‘a’ and ‘an’ are indefinite articles.”
• Indefinite pronouns refer to no specific person or thing: someone, anyone, no one, everyone, something, anything, each, every, some, any, few, many. Collins records “any” explicitly as an indefinite pronoun. They are called indefinite for the same reason the articles are — they do not pin down exactly who or what is meant.

The logic is consistent across all three senses: definite points at something specific and fixed; indefinite leaves it open. “A dog” (indefinite — which dog?) versus “the dog” (definite — that one).

How to use “indefinite” in sentences

Time with no fixed end:

• “The project has been postponed for an indefinite period.” (Cambridge’s own example)
• “Their plans have been put on indefinite hold.” (Merriam-Webster’s example)
• “She was granted indefinite leave to remain.” — a formal immigration term meaning permission with no expiry date.

Vagueness or lack of commitment:

• “He gave an indefinite answer when asked about the deadline.”
• “We’re stuck here for an indefinite period of time.” (Merriam-Webster)
• “She is indefinite about her plans.” (Merriam-Webster) — notice the word used of a person, meaning undecided or noncommittal.

Quantity or extent not fixed:

• “An indefinite number of people attended the meeting.” (Cambridge’s example)
• “The border between the two regions remains indefinite in places.”

The word sits naturally in official, administrative, and legal language — contracts, policies, immigration rules — because that is where unspecified limits matter most. In casual speech, “we’ll wait an indefinite amount of time” would sound stiff; “we’ll wait a while — no idea how long” is the natural version.

Indefinite vs infinite vs undefined

Three words that get mixed up because they all orbit the idea of “no fixed boundary”:

Word	Means	Example
Indefinite	No fixed or specified limit — but a limit could be set later	“An indefinite delay” (it will end; we just don’t know when)
Infinite	Without end; endless by nature	“The seemingly infinite universe”
Undefined	Not given a definition or explanation	“An undefined term in the contract”

The key distinction: indefinite is about limits that haven’t been set; infinite is about limits that don’t exist. An indefinite prison sentence is one with no fixed release date — it is not an infinite one. And undefined is about meaning, not limits: a word can be undefined without anything being indefinite about it.

The direct opposite of indefinite is definite: “a definite answer,” “a definite date,” “the definite article.”

Common mistakes

Spelling it “indefinate.” The ending is -ite, inherited from definite via Latin indēfīnītus. If you can spell definite, you can spell indefinite: just add in-.

“A indefinite” instead of “an indefinite.” Because indefinite begins with a vowel sound, it takes an: “an indefinite period,” “an indefinite answer.” This is a neat irony — the indefinite article itself changes form before the word indefinite.

Reading “indefinite” as “endless.” An indefinite postponement is not necessarily a long one; it is one with no date attached. “The talks were suspended indefinitely” means no resumption date was set, not that they will never resume.

Using it as a noun. Indefinite is an adjective only in the dictionaries checked — “an indefinite of time” is not grammatical. If you need the noun, indefiniteness exists, but rephrasing (“the vagueness of the plans”) is usually more natural.

FAQs

What is the opposite of “indefinite”?
Definite. Where indefinite means not fixed, not exact, or not identified, definite means fixed, exact, and identified: a definite date, a definite answer, the definite article the.

What does “indefinite leave” mean?
Time off with no set end date — most commonly “indefinite leave to remain,” the UK immigration term for permanent residence with no expiry. The indefinite part means no limit was fixed, not that the leave can never end.

What are the indefinite articles?
A and an — the articles used before a noun that hasn’t been specifically identified (“a book,” “an idea”). Their counterpart is the definite article the.

Is “indefinite” a formal word?
It is neutral rather than formal, but it clusters in official and administrative contexts — policies, contracts, HR, immigration — because those are the places where unspecified limits need naming. In everyday conversation, people more often say “not sure yet,” “up in the air,” or “no idea how long.”

What’s the difference between “indefinite” and “undetermined”?
They overlap heavily. Undetermined stresses that no decision has been made yet (“the cause is undetermined”); indefinite stresses that no limit or fixed form exists (“an indefinite postponement”). In many sentences they are interchangeable.

The takeaway

Indefinite means not marked out — no exact description, no fixed limit, no specific identity. That one idea runs through all its uses: the vague answer, the open-ended postponement, and the articles a and an that introduce something not yet identified. Spell it with -ite like definite, pair it with an not a, and don’t confuse it with infinite: indefinite limits can still be set — they just haven’t been yet.