FORMEDON, old English law. The writ of formedon is nearly obsolete, it having been superseded by the writ of ejectment. Upon an alienation of the tenant in tail, by which the estate in tail is discontinued, and the remainder or reversion is by the failure, of the particular estate, displaced and turned into a mere right, the remedy is by action of formedon, (secundum formam doni,) because the writ comprehends the form of the gift. This writ is in the nature of a writ of right, and the action of formedon is the highest a tenant in tail can have. This writ is distinguished into three species; a formedon in the descender, in the remainder, and in the reverter. 8 Bl. Com. 191 Bac. Ab. h. t.; 4 Mass. 64.