Tulle is a very fine net cloth, made of silk, nylon, or cotton, with tiny holes all over it so you can see through. It is light enough to float, and it holds air, so when you use many layers it puffs out instead of hanging down. That is why it is the cloth of ballet skirts — a tutu is layer upon layer of tulle — and of wedding veils, and of the stiff underskirt that makes a party dress stand away from the legs. Bridal shops and dressmakers use the word every day; most other people only meet it there. The sound is the trap: it is said "tool", exactly like the tool you fix things with. Not "tull", not "too-lay". Because it is a material, it is uncountable — you buy three metres of tulle, not three tulles — and it usually sits in front of another noun: a tulle veil, a tulle skirt. If you want a piece of it you say a length of tulle or a layer of tulle. The name comes from Tulle, a town in central France where the stuff was first made, so the word is really a place pretending to be a fabric — the same trick as denim (from Nîmes) and jeans (from Genoa).