Merino wool
A fine-fiber wool from Merino sheep — softer, less itchy, and more breathable than standard wool. Used in everything from base layers to mid-weight knits.
Merino wool comes from Merino sheep, a breed originally Spanish but now overwhelmingly raised in Australia and New Zealand. The fiber diameter is the defining trait: standard wool runs 30+ microns and feels scratchy against most skin; merino runs 18–24 microns, fine enough to wear directly against the body. The finest grades — 16-micron "ultra-fine" merino — feel closer to silk than wool.
The practical advantages: warmth-to-weight, temperature regulation, odor resistance, and surprising durability. A 200gsm merino tee weighs about the same as a cotton tee but stays warm when wet, dries faster, and doesn't hold body odor the way cotton does. The military and outdoor industries figured this out first; brands like Wool & Prince and Smartwool brought it into everyday menswear.
The tradeoff is cost and care. Merino is more expensive than cotton at the same weight (often 3–5×) and most pieces need cold-water wash + lay flat to dry. It also pills more readily than cotton until the fibers stabilize after a few washes.
Look for the micron count when brands publish it — that's the real quality signal. "Merino" alone could mean anything from 24-micron base layer to 16-micron ultra-fine. The lower the number, the finer and softer the fabric.
Cashmere
A luxury wool from cashmere goats — extremely soft, lightweight, and warm. Quality varies enormously; price is a rough proxy.
GSM
Grams per square meter — the standard unit for fabric weight. Higher GSM = heavier, denser, often more durable.
Pilling
Small balls of tangled fibers that form on fabric surfaces from friction. Tells you about fiber quality, knit construction, and how the garment was made.