1. Of grey tinged with brown
   - brown-grey [Brit, Cdn], brown-gray [US], brownish-grey [Brit, Cdn]

See also: achromatic, neutral

• family Unionidae
• family unit
• family Upupidae
• family Uranoscopidae
• family Ursidae
• family Urticaceae
• family Usneaceae
• family Ustilaginaceae
• family Valerianaceae
• family Varanidae
• family Veneridae
• family Verbenaceae
• family Vespertilionidae
• family Vespidae
• family Violaceae
• family Viperidae
• family Vireonidae
• family Viscaceae
• family Vitaceae
• family Vittariaceae
• family Viverridae
• family Viverrinae
• family Volvariaceae
• family Volvocaceae
• family Vombatidae