Webster's Revised Unabridged Dictionary · 1913

Plancher

Plancher , noun

[French, planche. See Planch.]

1.
A floor of wood; also, a plank. [Obsolete] — Bacon
2.
(Architecture) The under side of a cornice; a soffit.

Plancher , transitive verb

To form of planks. [Obsolete] — Golding