English UsageComparison guide

In Between vs. In-Between vs. Inbetween

Use “in between” as a two-word phrase when something is between two points, times, states, or items. Use the hyphenated “in-between” when it functions as an adjective meaning intermediate. The closed form “inbetween” is not the standard dictionary form for these ordinary uses.

Quick answer

Use “in between” as the ordinary phrase and “in-between” as the adjective before or after a noun when it means intermediate. Avoid treating “inbetween” as the standard spelling.

Key details

Core difference“In between” is the ordinary phrase; “in-between” is a documented adjective; “inbetween” is not the standard dictionary headword for these uses.
Rule Familyword-boundary-and-hyphenation
Termsin between, in-between, inbetween

Further guidance

Adjective Use

Use “in-between” when the expression functions adjectivally to mean intermediate or between two recognized states.

Closed Form Boundary

Do not generalize corpus appearances of “inbetween” into a standard spelling rule; the reviewed dictionary treatment distinguishes the open phrase and hyphenated adjective.

Phrase Use

Use the open form “in between” when the words operate as the phrase meaning between two times, places, states, or choices.

Sources and evidence

Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.

  1. In between — English meaning (opens in a new tab)Cambridge University Press · Dictionary treatment distinguishing the phrase “in between” from the hyphenated adjective “in-between”

Related guides

English Usage

Catch-Up vs. Catch Up vs. Catchup

Use open “catch up” for the phrasal verb and hyphenated “catch-up” for the ordinary noun or attributive adjective. Cambridge also records closed “catchup” in narrower combinations such as “catchup TV,” so it should not be generalized as the default spelling for every noun or verb use.

English Usage

Pro Forma vs. Proforma vs. Pro-Forma

For the general English expression, major dictionary treatment favors the two-word form “pro forma.” Cambridge also records “proforma invoice” as a variant within that business compound, so the closed form should not be generalized into a universal spelling rule.

Explore the topic