What is difference between monoploidy and haploidy?

Monoploid refers to the number of chromosomes of the cell, meaning that the cell has only one chromosome from every one of the "n" pairs (n=23 for the human cells). Haploid strictly refers to the number of chromosomes in the germ cells, which is half of the number of chromosomes normal cells have. Human germ cells are also haploid and monoploid. However, there are species in which the germ cells have more than one of each type of chromosome. This cells are haploid, but they are not monoploid.