• A long coil of yarn or hair intended for weaving, dyeing, or heat setting. Yarn sold in skeins often needs to be re-wound into spools or balls using a swift depending on the application. A skein is not a specific unit of length.
• The flight of a flock of undomesticated fowl such as wild mallards or wild geese
• Skein relation, a mathematical concept often used to give a simple definition of knot polynomials
• A winning streak in sports
• Fish eggs still held in the membrane, harvested from unripe fish ie: salmon or trout skein, used as fishing bait to catch the same.

In popular culture

• The Tangled Skein, a novel by Baroness Orczy
• With a Tangled Skein, a novel by Piers Anthony, book three of Incarnations of Immortality
• Skein, a fictional supervillain in the Marvel Comics universe