The description of the word you requested from the astronomical dictionary is given below.
A moon of 135 km diameter at about 66,100 km from the planet Uranus. The gravity at its surface is about 0.0025 times as strong as on Earth. The moon goes once around its planet in about 12.3 hours. The moon was discovered in 1986. Also called UXII (Uranus twelve). Its provisional designation was S/1986 U1.