A 4 way lycra means a fabric stretches and recovers both width and lengthwise. Fabrics using or that are nylon/Lycra are an example of four-way stretch fabric. If it does not stretch then it is two-way fabric. If it does then you know you have 4 way stretch in that knit selection. Another way to tell is by the softness of the fabric. 4 way feels softer than two ways. The stretch fabrics, such as spandex, stretches in both directions, crosswise and lengthwise. It is distinct from elastic which is not a fabric but a notion. 4 way lycra is very comfortable.