Usually occurring at the beginning or end of a sentence, a genitive absolute is a grammatical construction used in the Greek language. Included in a participle, a genitive absolute indicates the subject of the participle is not the same subject as the main sentence. This construct is necessary in Greek because Greek verbs are otherwise automatically paired with the subject of the main sentence. Genitive absolutes are denoted by a change in spelling of both verb and noun in the participle.
The verb in a participle usually functions as a descriptor, or adjective, rather than denoting an action. Participles may be a word or a phrase and, in English, usually end in "-ing" or "-ed" for the present and past tense respectively. For example, in the sentence "While running, the girl tripped and fell," the phrase "while running" is the participle. Running describes what she was doing when the action in the main sentence occurred.
Words that are in the genitive case usually have endings which show ownership of one thing to another. In English, it is often expressed by an apostrophe and the letter s, for example, "the king's crown." The construction of a genitive absolute is named such because it links a particular verb to a particular subject, in a sense showing the subject's ownership of the verb.
In Greek, a genitive absolute only occurs when the subject in the participle differs from the subject of the sentence. For example, in the sentence, "When Victor reached the airport, Sasha had already boarded the plane," Victor is the subject of the participle, but Sasha is the subject of the main sentence. While English verbs do not change to indicate gender, in Greek they do.
Without the genitive absolute, both the words "reached" and "had boarded" would have a feminine ending, referring to Sasha. The genitive absolute changes the ending of "reached" to reflect that the reaching action belongs to "Victor." It also changes the ending of "Victor" to indicate that it is the noun "reach" is connected to.
The difference in the subject of the participle and the main sentence may also be caused by a mix of plural and singular pronouns. In this case, a singular noun may be included in a plural noun, but singular and plural are still considered different subjects. For example, in the sentence "After they went shopping, she put away the groceries." The pronoun "they" in the participle includes the "she" in the main sentence, but since one pronoun is singular and one is plural, the genitive absolute would be used.