Another is much more common in English than “an other”. It means one more or additional. We use “other” when we have more than “one more”.

The biggest difference between these two words is that “another” is always singular and does not describe anything specific. “Other” is used for plural and noncount nouns that are general. We only use “the other” to refer to specific nouns.

The primary difference between another and other is that both another and other are determiners, but another precedes singular countable nouns or pronouns. Conversely, other precedes a plural countable as well as uncountable nouns and pronouns.

On the other hand, “an other” is less common and usually appears in sentences where “other” is a noun or when there’s a clear separation between “an” and “other.” For example, “She wanted a dress in an other color.” However, this usage is rare, and often, “another” is the correct choice. So, when in doubt, go with “another.”

Hint: If you understand English articles ("a/an/the"), then think of "another" as "an + other." You can use "another" before a noun whenever you can use "a (n)" before a noun. The rules are the same. Another = an other! other + plural or uncountable nonspecific noun