Lyocell is a fiber made from the cellulose in wood pulp. This fiber is used to create yarns that are then made into fabrics from which clothing and other textile items can be made. It is considered to be an environmentally friendly product. The wood pulp comes from managed forests, the low-impact production process uses non-toxic materials, and the final product is biodegradable.
Lyocell clothing is usually machine washable on the gentle cycle, but check the tags, as linings or other aspects of its fabrication may require the item to be hand washed or dry cleaned. Drip dry, though you can usually put the already dry article into a clothes dryer with a damp towel for a few minutes to loosen it up. It dries very quickly, resists shrinkage, is wrinkle-resistant and it wears like iron.
I can tell you from personal experience that it is lightweight, breathes well, and is very soft. It is absorbent, but yet it doesn't race to show perspiration, either. It looks, drapes, and feels like heavy silk — in other words, it is outrageously comfortable. If I could, I’d have all my clothing made from it!
A common trade name for lyocell is Tencel®.