This question already has an answer here:
If I said that we are living in a Universe with 3 time dimensions and 1 spatial dimension, would I be wrong?
By that I mean if the spacetime interval was evaluated as
-time1^2-time2^2-time3^2+space1^2 instead of
Is there an absolute difference between a spatial and a time dimension, or are they like the positive and negative electrical charges?
Edit: This came to me after reading a question considering more than 1 time dimensions. I think it was about a 2+2 universe, which prompted the question "Which 2 would be the time dimensions?"
So I guess the real questions is, is time's property the fact that it is a single dimension of its type/sign, instead of 3? Could we talk about spacetimes only for 1+N pseudo-euclidean spaces, but not for M+N where M>1 and N>1?
And also, if we have 3 time dimensions and 1 space dimension, and the spacetime interval was