Wann sind Wörter auf Englisch zusammengeschrieben z.B. rain jacket und wann getrennt z.B. raincoat?

Wenn es keine Regel gibt, muss man die Schreibweise einfach lernen mit dem Vokabeln.

Hallo,

nichts ist in Stein gemeißelt, häufig hängt es von Vorlieben ab,

... the styling that ultimately takes hold for a compound may be determined by nothing more than editorial and writerly preference, ...

...

Compound nouns, for instance, are usually written as one word; compound verbs are generally written as two; compound adjectives are often written with a hyphen. But note that we added "usually," "generally," and "often"—we're hedging. (Be advised that we'll be using noncommittal terms throughout, and, essentially, that's the point of the following articles: there aren't fast rules to forming compounds, but there are patterns.)

(https://www.merriam-webster.com/grammar/spelling-using-compound-words-guide)

AstridDerPu