horsehair lichen: any of several lichens of the genus Alectoria having a thallus consisting of filaments resembling hair
lichen: any thallophytic plant of the division Lichenes; occur as crusty patches or bushy growths on tree trunks or rocks or bare ground etc.
nautical mile: a unit of length used in navigation; exactly 1,852 meters; historically based on the distance spanned by one minute of arc in latitude