Outta is not a separate word with its own job. It is how writers put the spoken sound of out of on the page. When people talk fast, the two words run together — “Get outta here,” “I’m outta money” — and song lyrics, texts, and story dialogue often spell that rush as one word. Teachers still want out of in essays and news; outta is a picture of a voice, not the careful spelling. It can feel very American and very casual. Older or more formal speakers may still say out of as two clear words, and they are not wrong. If you see it, read it as out of and hear someone talking, not giving a lesson.

out of 的口語連寫（非正式）