Webster's Revised Unabridged Dictionary · 1913

Weathercock

Weathercock , noun

1.
A vane, or weather vane; -- so called because originally often in the figure of a cock, turning on the top of a spire with the wind, and showing its direction.
As a wedercok that turneth his face with every wind. — Chaucer
Noisy weathercocks rattled and sang of mutation. — Longfellow
2.
Hence, any thing or person that turns easily and frequently; one who veers with every change of current opinion; a fickle, inconstant person.

Weathercock , transitive verb

To supply with a weathercock; to serve as a weathercock for.
Whose blazing wyvern weathercock the spire. — Tennyson