Answer:
What did Lincoln mean by consecrate? To consecrate means to declare something holy and hallow is its synonym. Lincoln is saying that the ground cannot be declared holy, because: The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract
Lincoln means that the extreme sacrifice the men who had fought and died on that battlefield have made was in itself a greater act than any other could now, or ever, perform in ordaining the soil on which they died. Their deed was more than enough for the ground to be consecrated. The living can honor the wartime dead not with a speech, but rather by continuing to fight for the ideas they gave their lives for.