also: ずっとも
noun
friends forever; BFF
Slang abbreviation of ずっと友達. Used mainly by young people in casual contexts, often online or in texting.
私たち、ズッ友だよね！
We're friends forever, right?
卒業してもズッ友でいようね。
Let's stay BFFs even after graduation.
Abbreviation of ずっと友達 (zutto tomodachi, 'friends forever'), with the first part written in katakana for emphasis or stylistic effect.