What does ablative mean?
The definition of ablative
Ab”la*tive, a.
Etym: [F. ablatif, ablative, L. ablativus fr. ablatus. See Ablation.]

1 Taking away or removing. [Obs.] Where the heart is forestalled with misopinion, ablative directions are found needful to unteach error, ere we can learn truth. Bp. Hall.
2 (Gram.)
Applied to one of the cases of the noun in Latin and some other languages, — the fundamental meaning of the case being removal, separation, or taking away.

Ab”la*tive, (Gram.)
The ablative case. ablative absolute, a construction in Latin, in which a noun in the ablative case has a participle (either expressed or implied), agreeing with it in gender, number, and case, both words forming a clause by themselves and being unconnected, grammatically, with the rest of the sentence; as, Tarquinio regnante, Pythagoras venit, i. e., Tarquinius reigning, Pythagoras came.