Webster's Revised Unabridged Dictionary · 1913

Formedon

Formedon (fôr"me*don) , noun

[Old French, from Latin. So called because the plaintiff claimed “by the form of the gift,” Latin per formam doni.]

(O. Eng. Law) A writ of right for a tenant in tail in case of a discontinuance of the estate tail. This writ has been abolished.
by the form of the gift,