means A slim, pointed metal spike driven into wood or other material to fasten things together — or, on a finger or toe, the hard protective plate of keratin at the tip.

from From Old English 'nægel,' which covered both the metal fastener and the fingernail — a double meaning that runs deep through the Germanic languages (compare German 'Nagel,' Dutch 'nagel'). It traces back to a Proto-Indo-European root '*(o)nogh-,' the same ancient source that, through Latin, gives us 'nail' words across Europe. The shared name for spike and fingernail isn't a coincidence — both are hard, pointed things at the end of something, and our ancestors clearly saw the resemblance long before they were hammering iron.