- nail (n.) - Old English negel "metal pin," nægl "fingernail
(handnægl), toenail," from Proto-Germanic *naglaz (cf. Old Norse
nagl "fingernail," nagli "metal nail;" Old Saxon and Old High
German nagel, Old Frisian neil, Middle Dutch naghel, Dutch
nagel, German Nagel "fingernail, small metal spike"), from PIE
root *(o)nogh "nail" (cf. Greek onyx "claw, fingernail;" Latin
unguis "nail, claw;" Old Church Slavonic noga "foot," noguti
"nail, claw;" Lithuanian naga "hoof," nagutis "fingernail;" Old
Irish ingen, Old Welsh eguin "nail, claw"). The "fingernail"
sense seems to be the original one. Nail polish attested from
1891. To bite one's nails as a sign of anxiety is attested from
1570s. Nail-biting is from 1805. Hard as nails is from 1828. To
hit the nail on the head "say or do just the right thing" is
first recorded 1520s. Phrase on the nail "on the spot, exactly"
is from 1590s, of obscure origin; OED says it is not even
certain it belongs to this sense of nail. - nail (v.) - Old
English næglian "to fasten with