Bedding & Sleepwear Glossary

Bedding and sleepwear labels are full of words that sound like specifications but are often used loosely. These are the terms we get asked about most, defined in plain English. Where one of our own fabrics is an example, we say so and give the real figure.

By Snoozyn · Updated September 2026. Teachers, students and bloggers are welcome to link to or quote any definition.

Weaves and weights

Thread count (TC)
The number of threads woven into one square inch of fabric, counting both directions (warp and weft). A higher number is not automatically better: very high counts are often reached by twisting several thin yarns together. Our Plain Cotton and Cloud Cotton are 200 TC, and Silky Cotton is 300 TC.
GSM
Grams per square metre, a measure of how heavy a fabric is. It is the useful number for linen and knitted jersey, where thread count means little. Our linen is 170 GSM.
Momme (mm)
A Japanese unit for the weight of silk; one momme is roughly 4.34 grams per square metre. Most silk sleepwear sits between 16 and 25 momme. We make 19 and 22 momme pyjamas; what is momme? explains the difference.
Percale
A plain weave, one thread over and one under, which gives a matte, crisp cotton that feels cool to the touch. Our Plain Cotton is a percale. See percale vs sateen.
Sateen
A weave that floats more threads on the surface (typically four over, one under), giving cotton a smooth face and a soft sheen. It shows creases a little more readily than percale. Our Silky Cotton is a sateen.
Double gauze
Two layers of fine, loosely woven cotton gauze joined at intervals, which leaves a crinkled, airy cloth. Cloud Cotton is our name for double gauze; what is cloud cotton? goes into the detail.
Satin
A weave, not a fibre: long surface floats create a glossy face. Satin can be woven from silk or from polyester, which is why "satin" on a label tells you nothing about the fibre. See silk vs satin.
Charmeuse
A light satin-weave silk with a glossy face and a duller back, often used for sleepwear and lingerie.
Jersey
A knitted fabric rather than a woven one, made from interlocking loops, so it stretches in every direction. T-shirts and most modal sleepwear are jersey.
Woven vs knitted
Woven fabrics interlace two sets of threads at right angles and hold their shape; knitted fabrics loop a single yarn and give with movement. Bedding is almost always woven; soft sleepwear is often knitted.

Fibres

Long-staple cotton
Cotton with longer individual fibres, which spin into a finer, smoother and stronger yarn with fewer loose ends. All our woven cotton bedding is long-staple.
Egyptian cotton
Cotton grown in Egypt, historically prized for extra-long staples. The name describes an origin, not a grade, so the label alone does not guarantee quality; which cotton is best for bedding? explains what to check instead.
Flax and linen
Linen is the fabric; flax is the plant it is spun from. Linen is heavier and more textured than cotton and softens with washing. Our linen is pure French flax. See linen vs cotton bedding.
Mulberry silk
Silk from the Bombyx mori silkworm, raised on mulberry leaves. Its long, even filaments give the smooth, lustrous cloth most people mean by "real silk".
A soft fibre made from dissolved beech wood pulp: plant-based but semi-synthetic, and a member of the viscose family. See what is modal fabric? and modal vs cotton.
Viscose (rayon)
The family name for fibres regenerated from plant cellulose. Modal, lyocell and "bamboo" fabrics all belong to it; the labels explained.
Lyocell (TENCEL™)
A regenerated cellulose fibre made by a solvent-spinning process; TENCEL™ is a brand name for lyocell and modal made by Lenzing.
Elastane (spandex, Lycra®)
A synthetic stretch fibre blended in small amounts so a garment moves and recovers its shape. Our Modal Cloud sleepwear is 95% modal and 5% elastane.
Microfibre and hollowfibre
Polyester fillings for duvets and pillows. Microfibre uses very fine fibres; hollowfibre uses thicker hollow strands. Our duvet and pillow inserts are filled with micro-denier polyester.

Construction and finish

Stonewashing
Tumbling finished fabric, traditionally with stones, to break in the fibres, so linen arrives soft rather than stiff. Our linen is stonewashed.
Piping
A narrow folded strip sewn into a seam as a contrast edge. Our piped Cloud Cotton sets use it around the duvet cover and pillowcases.
Two-tone
A duvet cover with a different colour on each side, so the bed can be turned to change the look.
Housewife pillowcase
A pillowcase closed by an internal flap at one end, with no buttons or zip, the most common style in the UK.
Oxford pillowcase
A pillowcase with a flat border of fabric (a flange) stitched around its edge.
Monogram
Initials embroidered onto a piece. Ours are hand-embroidered in our London atelier; see personalise.
Made to order
Made after the order is placed rather than taken from stock. Our made-to-order colours ship within 3 to 6 days.
Pilling
Small balls of fibre that form on a fabric's surface where it rubs, usually from short or loose fibres working free.

Duvets, sheets and sizes

Duvet (quilt, comforter)
A soft, flat bag of filling used as the top layer of a bed inside a removable cover. "Quilt" is common in the UK too; "comforter" is the American term for a similar but usually uncovered layer.
Tog
The UK measure of how warm a duvet is, from its thermal resistance. Around 4.5 tog is a summer weight, 10.5 tog an all-season weight and 13.5 tog a winter weight. Our duvet insert is 10.5 tog.
Fitted sheet
A sheet with elasticated corners cut to a mattress's width, length and depth. Our standard fitted sheets suit mattresses up to 35 cm deep.
Flat sheet
A plain rectangle of fabric used under a duvet or tucked over the mattress. A double flat sheet is 230 × 260 cm.
Drop
How far a duvet hangs over each side of the mattress. A double duvet on a double bed gives about 32 cm.
UK bed sizes
Single 90 × 190 cm, small double 120 × 190 cm, double 135 × 190 cm, king 150 × 200 cm and super king 180 × 200 cm. Size by size: single, double, king, super king, or all of them together.
Continental (EU) sizes
Mattresses measured in round centimetres, such as 140 × 200 or 160 × 200 cm. Apart from 180 × 200 cm, they do not match a UK size, so UK sheets fit poorly; we cut to your measurements.

Care and labels

Moisture regain
How much moisture a dry fibre takes up from the air under standard conditions, as a percentage of its weight: roughly 8.5% for cotton and about 12% for linen. It is one way of comparing how fabrics handle damp.
Breathability
How easily air and water vapour pass through a fabric. It depends on the fibre, the weave or knit, and the weight.
Colourfastness
How well a dye resists fading or running in washing and light.
Shrinkage
The reduction in size when a fabric is washed or dried, usually from heat. Our care guide gives the wash settings for each fabric.
OEKO-TEX®
An independent testing and labelling scheme that checks textiles for harmful substances. A product can only use the label if it has been certified. We do not hold OEKO-TEX certification.
Organic cotton
Cotton grown under certified organic standards, usually shown by a scheme such as GOTS. The word only means something when the certificate is named. We hold no organic certification on any of our fabrics.

Still choosing? The bedding fabric guide compares our four bedding cloths, and the pyjama fabric guide does the same for silk, modal and cotton.