A fishhook fastener is a type of knot used to secure a fishing line to a hook. The most common type of knot used for this purpose is the Snell knot, which is a five-letter word. The Snell knot is a strong and reliable knot that is easy to tie and can be used with any type of fishing line. It is also very resistant to slipping or coming undone, making it an ideal choice for securing a fishhook fastener.