Complex sentence: Its name is an acronym from "Triangle Below Canal Street"; the "triangle"--actually closer to a trapezoid, or a triangle with the peak cut off--is bounded by Canal Street, West Street, Broadway, and Vesey Street.
Split into simpler sentences: Its name is an acronym from "Triangle Below Canal Street", but this name is a misnomer, as the area is not a triangle. The area is properly bounded by Canal Street, West Street, Broadway, and Vesey Street.