Mare'S-Tail

Part of speech: noun (n.)

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 mare's-tails Make tall ships carry low sails. Old Rhyme.

2. An aquatic plant of the genus Hippuris (H.vulgaris), having narrow leaves in whorls.