Jeggings are leggings which are styled to look like tight denim jeans.

The ‘j’ not only refers to the appearance of denim, but also to the fact that they were first worn for jogging in early 2009. Apart from the ‘jean’ adaptation, some jeggings are made with a new type of nylon named nylon PV1.

I consider jeggings to reside in the same phylum as pyjama jeans.