筷 is almost exclusively used in 筷子 (kuàizi, chopsticks). The measure word is 双 (shuāng, pair) or 根 (gēn, single stick). The 竹 radical on top indicates bamboo, the original material.
culture
Chopstick etiquette: never stick chopsticks upright in rice (it resembles funeral incense), and never point at people with them.
