When to use "between" and when to add an in and say "in between" has become clear from the two very related SE posts: "In between" or "between"? and 'in between' or 'between'. Apparently the in can always be omitted but is optional to add when "between" is used as a preposition for physical (and apparently also time-wise) comparisons:

There is a puddle [in] between us. Optional "in"

There is some tension between us. Don't use "in"

Question 1: Is this always correct? Are there never situations where the in is mandatory?

Question 1a: And equivalently, in order for me to understand the proper usage: what difference does the word in make in the sentence? Does it not make a difference? Can I safely omit the in completely in any context and never bother with this again?

When I do choose to use the in in relation to between there apparently are several options:


in between


The two first-mentioned seem well-explained in Should I use "in between" or "inbetween" in the following sentence?: the "in-between" is an adverb. But an answer in that post indicates that the latter form "inbetween" with no dash or space does exist.

Question 2: What exactly is the difference and meaning of these three versions? And do they all exist?

1 Answer 1


Question 1. and 1.a) I doubt that the preposition in is ever required. It likely has to do with regional usage and style rather than correctness. E.g. British English vs. American english. See: https://www.quickanddirtytips.com/education/grammar/prepositions?page=1

Question 2.) According to this answer and Merrium Webster, In-between is an (adjectival) noun or idea. For example, one could say "We are in the in-between phase of this plan." "In between" can be thought of as an adverbial phrase as in, "The interviewer and interviewee were sandwiched in between two ferns."

  • I agree with this answer and appreciate the reference to the show “Between Two Ferns”. Also wanted to point out that (as mentioned in the other linked question) “inbetween” is an animation term: en.m.wikipedia.org/wiki/Inbetweening
    – Mixolydian
    Feb 15, 2019 at 23:58

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .