Lifetime or Life time – What’s the Difference?

There are many words in English that mean a long time. One could speak of forever, an eternity, an infinity, or a lifetime. Interestingly, all of these words are frequently used figuratively to describe even short durations where nothing interesting is happening, like in the phrase this is taking forever. It would seem English speakers are not a patient group.

Regarding lifetime, should you use it as one word, or as two separate words, as life time? You may have seen both versions in your reading.

The answer is simple and involves the process in English that shortens multi-word phrases into single words for easier use.

What’s the Difference Between Lifetime and Life Time?

In lifetime one word? In this post, I will compare lifetime vs. life time and outline which variation you should use in your writing.

Plus, I will also show you a helpful mnemonic device that makes choosing either lifetime or life time simple

When to Use Lifetime

lifetime versus life time What does lifetime mean? Lifetime is a noun. It means the span of time beginning when a person is born and ending when the person dies. Since some people live longer than others, it is not an exact measurement.

Lifetime is often used figuratively to describe an inordinate length of time, especially if whatever is happening during it is not terribly interesting.

Here are some examples,

  • “This seminar is taking a lifetime,” said a bored attendee. (Figurative)
  • Ghandi spent a lifetime spreading liberty and civil rights wherever he went. (Literal)

Lifetime can also be an adjective, where it describes something that lasts until a person dies, like a prison sentence or an award.

For example,

  • No one was surprised when the ax murderer was handed a lifetime sentence for his crimes.
  • I honored myself with a lifetime achievement award for passing my capstone class in college.

When to Use Life Time

define life time define lifetimeWhat does life time mean? Life time is a two-word variant of the same term.

Over time, the English language compounds many phrases that once began as separate words, resulting in a single word. The same phenomenon has taken place with race car (forming racecar) and smart phone (to form smartphone).

Here’s an example of life time in a sentence,

  • Jaylen thought he would suffer a life time of sorrow after Genieve broke up with him.

In the chart below, you can see the relative usage of life time vs. lifetime in English,

definition of life time definition of lifetime definition

As you can see, lifetime is clearly preferred and has been since at least 1800. The compounding process has been decisive for these words.

Trick to Remember the Difference

For at least the last two centuries, writers have strongly preferred lifetime to life time. You should do the same in your own writing.

Since lifetime is a single word, like its fellow compounds goalpost and bedpost, it’s easy to remember to use it.


Is it life time or lifetime? Lifetime is an adjective and a noun that means the duration of a person’s life. It is a compound of the two-word phrase lifetime, and today, the single word version predominates.

To summarize,

  • Lifetime is one word.
  • Life time is an incorrect spelling.

The word appears to have been compounded at least 200 years ago.