Lifetime is one word. Not “life time,” not “life-time” — just “lifetime,” spelled as a single closed compound. It’s the correct form whether you’re talking about a lifetime warranty, a lifetime of memories, or the lifetime of a battery.
This one trips people up because “life” and “time” are both common standalone words, and English loves to keep some compounds split (“life span,” for instance, is still two words in most style guides). But “lifetime” made the jump to a single fused word decades ago, and every major dictionary — Merriam-Webster, Oxford, Cambridge — lists it that way with no hyphen and no space.
The Short Answer
Write it as “lifetime” in every standard context: “a once-in-a-lifetime opportunity,” “lifetime achievement award,” “she spent a lifetime studying birds.” There’s no acceptable two-word version (“life time”) in modern American or British English. If spellcheck flags “life time,” that’s your sign to close it up.
Where the Confusion Comes From
- It looks like two ideas. “Life” and “time” are both meaningful on their own, so writers instinctively want to separate them.
- Related phrases stay split. “Life span,” “life expectancy,” and “life story” are all two words, which makes “lifetime” feel like it should follow suit.
- Old texts sometimes hyphenated it. A century ago “life-time” appeared in print. Language evolved, and the hyphen dropped out, the same way “to-day” became “today.”
Is There Ever a Two-Word Version?
Almost never — but there’s one narrow exception. If “life” is modifying a separate noun “time” in a very literal, non-idiomatic sense (rare, and usually reworded anyway), you could technically split it. In practice, professional writers, editors, and dictionaries treat this as a non-issue: “lifetime” is always one word when you’re using it as a noun meaning “the duration of someone’s or something’s existence,” or as an adjective meaning “lasting for the whole of a life” (as in “lifetime membership”).
Examples in a Sentence
- The blender comes with a lifetime warranty.
- He said it was the best meal of his lifetime.
- She built a lifetime of trust with her clients.
- This is a once-in-a-lifetime chance to see the eclipse.
- The company offers lifetime access to the course.
Lifetime vs. Related Terms
| Term | Spelling | Meaning |
|---|---|---|
| Lifetime | One word | The whole duration of a life or existence |
| Life span | Two words | The typical length of time something lives |
| Lifelong | One word | Lasting an entire life (as an adjective) |
| Life story | Two words | The narrative of someone’s life |
Key Takeaways
- “Lifetime” is always one word — no hyphen, no space, in any standard writing context.
- “Life time” as two words is considered incorrect by every major dictionary.
- Related terms like “life span” and “life story” stay split — don’t let those confuse your spelling of “lifetime.”
- It works as both a noun (“in her lifetime”) and an adjective (“lifetime guarantee”).
Frequently Asked Questions
Is “lifetime” one word or two words?
“Lifetime” is one word. It’s a closed compound, meaning “life” and “time” are fused together with no space or hyphen, and that’s the only correct spelling in standard English.
Is “life-time” with a hyphen ever correct?
No. While older texts sometimes hyphenated it, modern style guides and dictionaries have dropped the hyphen entirely. Stick with “lifetime.”
What does “lifetime” mean?
It means the entire length of time a person, animal, product, or thing exists or lasts — as in “a lifetime of experience” or “the lifetime of a light bulb.”
Why is “life span” two words but “lifetime” is one?
Compound words evolve individually based on how often and how long they’re used together. “Lifetime” became common enough, early enough, to fully merge, while “life span” hasn’t undergone that same shift in most style guides.
Can “lifetime” be used as an adjective?
Yes. In phrases like “lifetime warranty,” “lifetime membership,” or “lifetime achievement,” it functions as an adjective describing something that lasts for an entire life.
Once you know “lifetime” closes up into a single word, you’ll never second-guess it again. If compound-word mix-ups like this one trip you up often, it’s worth browsing more spelling comparisons on the site — they tend to follow the same handful of patterns.
