Bedding glossary: sizes, fabrics, fills and care terms
Find definitions for bedding sizes and fabric terms, with links to detailed guides.
Last updated October 2026
Use this bedding glossary to decode a size label or fabric term. Definitions describe the term; the exact product's dimensions and care instructions still decide how it fits and how you clean it.
Bedding terms from A to Z
Baffle box
Walls inside a filled item divide the fill into boxes. Check the actual item. A box stitch on the outside doesn't prove those walls are inside.
Blend
Cloth made with more than one type of fiber. Read each percentage. The first fiber in a short title doesn't tell you the whole mix.
Comforter
A filled top layer with a sewn shell that can be the visible bed covering. Check the label for fill, dimensions and care. See insert versus comforter.
Cotton
A plant fiber used to make several types of cloth. Cotton percale can feel different from cotton sateen. The fiber name alone doesn't settle the feel.
Down
Soft plumage used as filling. Read the actual composition and care label; a product name alone may not state every part of a blend.
Down alternative
A name for fill used in place of down. It doesn't tell you the exact fiber or how to wash it. Read the full label.
Drop
The fabric extending down the side or foot of a bed. A centered flat-bed side drop can be estimated from width; see the worked fit check.
Duvet cover
A shell you can take off a filled insert or comforter. It has an opening and may have corner ties. To fit a cover, check both items' measurements.
Duvet insert
A filled layer intended for use inside a removable cover. Its own care label still applies even when the outer cover is washable.
Duvet set
A pack built around a duvet cover, with the other pieces named in the listing. A filled insert is not automatically included. Check the contents list.
Envelope closure
A flap that folds over to enclose a pillow or other insert. It closes that opening without a button or zip.
Euro pillow
A square pillow format. A common chart gives 26 by 26 inches, but exact products vary. The name doesn't establish the filling or intended use.
Fitted sheet
A sheet with shaped corners and, usually, an elastic edge. It wraps around the mattress. Check the width and length as well as the height it fits.
Flange
A border outside the main insert space of a sham or cover. Check whether the listed size includes this extra edge.
Flat sheet
A rectangular fabric layer used as a top sheet or tucked as a bottom sheet in some setups. See flat versus fitted.
Gusset
A side panel that adds thickness at the edge. Width and length alone may not tell you the full size.
Jersey
A type of knit fabric. Check what the yarn contains too. Jersey doesn't mean pure cotton.
King
A size name whose exact meaning depends on the item. Mattress, comforter and pillow dimensions are different measurements. Use the size reference.
Linen
A textile fiber from flax. The word is also used broadly for household bedding, so read the composition when the material itself matters.
Loft
The height or fullness of a filled item in a stated condition. Uncompressed height doesn't establish how it feels under a person's head.
Lyocell
A made fiber from cellulose, the material in plant cell walls. Check the full fiber label and care. A plant name alone doesn't tell you how the sheet will perform.
Percale
A plain over-and-under yarn pattern. Cotton percale often feels crisp and looks matte. Read about percale to see why the pattern and fiber are separate facts.
Pillow protector
A cover beneath a pillowcase. Check its fit and care label. Using it doesn't make the filled pillow washable.
Ply
Strands twisted together into a yarn. Ask how a thread count is calculated if the counting basis matters to your comparison.
The shaped side area of a fitted sheet. Check whether a stated measurement means actual pocket height or the maximum mattress height it accepts.
Rayon
A made fiber from cellulose. Rayon made from bamboo isn't the same as cloth made directly from bamboo fiber. The FTC explains the label rule.
Sateen
A yarn pattern with longer runs on the face of the cloth. It often has a smooth feel and more shine. It doesn't mean silk. See percale versus sateen.
Sham
A pillow covering often used for decoration. Check the intended insert size; a sham is not automatically a filled pillow.
Thread count
A count of yarns in both directions over a stated area, commonly a square inch. It is not a full quality score. See the thread-count guide.
Twin XL
A common US mattress label for a longer twin footprint. Check actual dimensions before choosing a fitted sheet; a regular twin sheet may be too short.
Sources and corrections
For dimensions rather than definitions, use the comforter size reference and pillow size reference. A shared size name does not make their measurements interchangeable.
These definitions explain bedding terms in our own words, using the references below. Read the exact product label when choosing or caring for an item.
- CottonWorks.
- FTC textile guidance.
- The Company Store size FAQ.
- The maker references in the linked guides.
Use contact to suggest a correction, or return to bedding guides. An unknown search term gives no generated definition; clear the search to see all entries.