The word "frostnail" is spelled with a silent "n". The correct pronunciation is /frɒstneɪl/. The word refers to a small, pointed icicle formed when water droplets freeze and accumulate on an object. The "n" is not pronounced, and it is included solely for etymological reasons. The word is a combination of "frost" and "nail," with the latter referring to the shape of the icicle. This spelling may be challenging for non-native speakers and those unfamiliar with the word.