Haute means "high" in French. It is pronounced "hote", NOT "hot". It is used most commonly with the word "Couture" (pronounced catore) which means "fashion" in French. Thus, Haute Couture means High Fashion.
It does not, however, mean hawt, hot, sexy, whatever. People who use haute in place of those words are idiots who seriously need to read the REAL dictionary instead of urbandictionary.com.
That Vivienne Westwood trench is so haute couture.