Real Dictionary

ablative absolute in American English
in Latin, a grammatically independent phrase containing a noun in the ablative case and a participle, pronoun, or second noun also in the ablative case, used to express time, cause, or circumstance
noun: a construction not dependent upon any other part of the sentence, consisting of a noun and a participle, noun and adjective, or two nouns, in which both members are in the ablative case, as Latin viā factā, “the road having been made”

ablative absolute in British English
noun: an absolute construction in Latin grammar in which a governor noun and a modifier in the ablative case function as a sentence modifier; for example, hostibus victis, "the enemy having been beaten"