So as to augment or increase; in the manner of an augment.
The Century Dictionary (Public Domain)
Use "augmentatively" in a sentence
"As my explanations here are probably above your understand-ings, lattlebrattons, though as augmentatively uncomparisoned as Cadwan, Cadwallon and Cadwalloner, I shall revert to a more expletive method which I frequently use when I have to sermo with muddlecrass pupils."