What does ない mean?
ない is a Japanese noun meaning “there isn't, doesn't have” in English. It can also be translated as “unowned, unique, not” depending on context. It is written as ない in hiragana, and nai in romaji. This word is part of JLPT N5 vocabulary.
Example sentence
２つの意見に大した差はない。
There is not much difference between the two opinions.