Uneven-aged forest
A vegetal stand in which all ages are represented, in theory, up to those of the oldest tree, with a number of individuals progressively decreasing with age (source: “Selvicoltura generale" P. Piussi, UTET).

Unit of Livestock Adult (hereinafter referred to as UBA)
Unit of measurement of the consistency of a farm, which varies according to animal species and age.

Utilised agricultural area (hereinafter UAA)
Area of the holding used for agriculture.