Definify.com
Webster 1913 Edition
Mare's-tail
Mare’s′-tailˊ
,Noun.
1.
A long streaky cloud, spreading out like a horse’s tail, and believed to indicate rain; a cirrus cloud. See
Cloud
. Mackerel sky and
Make tall ships carry low sails.
mare's-tails
Make tall ships carry low sails.
Old Rhyme.
2.
(Bot.)
An aquatic plant of the genus
Hippuris
(Hippuris vulgaris
), having narrow leaves in whorls.