1) A measure of length, possibly because nails originally marked off sections of a yard-stick.
First noted in a translated Latin passage: 1418 ‘from the said outer corner ... towards the fyshelendyng 5 ells and a nayle large’, York. Subsequently it was used frequently as a measure of cloth: 1434 Et pro uno quarterio et nale rus velvet pro gladio maioris, York
1454 In j nayle panni empto et dato pro exemplo vesture estivalis iiijd, York
1642 Some linen cloath ... there is againe which is yard broad or yard and nayle, Elmswell.