The "no see um sock" is a type of sock specially designed to protect against biting insects such as mosquitoes and ticks. While this term is commonly used, there are also other synonyms that refer to the same type of sock, including insect shield socks, bug repellent socks, and mosquito-proof socks. These socks are made with a special fabric that repels insects or includes an insecticide treatment that kills them on contact. They are perfect for outdoor activities such as camping, hiking, and fishing. With their effective insect protection, these socks are a great investment for anyone who spends time in bug-infested areas.