It might help if you understand the historical order of the use of the word.
Crinoline was originally a material used to make petticoats in the 1840s to increase the width of the skirt without endless undergarments. It was made of horsehair and linen and didn't crush easily under its own weight. These were called crinoline petticoats, identifying the material and purpose of the garment. Eventually, they just became referred to as "crinolines."

With the introduction of the hoop skirt in the mid 1850s, crinolines were displaced by hoop skirts, but the term transferred from one to the other. Any skirt undergarment that created fullness came to be known as a crinoline. Essentially the large crinolines fell from fashion in the 1870s, as did the term, and we heard nothing about crinolines again. Then, in the late 1940s, those full multi-skirted and flounced nylon tulle and taffeta, or gathered and flounced nylon tricot petticoats intended for creating fullness in skirts came into use once again. Wedding, and some evening gowns also employed feather-bone stiffened petticoats, or hoop skirts, all of which became known as crinolines, so essentially, the material had nothing to do with the purpose of the garment or the term anymore, and the undergarment alone became known as a "crinoline". The nylon netting, or tulle, or any material used to make a crinoline after 1855 is not referred to as crinoline - it is the garment itself that is known by that name. 

50's Black Crinoline with red trim
Courtesy of northstarvintage

Tulle and organza Square Dance crinoline, these are shorter in length than the 50's crinolines. These are usually 23 to 25 inches in length
Courtesy of alonesolo/fashiontales