ad. Of such extremely small quantity or degree that it is not worth measuring.
the GNU version of the Collaborative International Dictionary of English
ad. without significance, importance, or effect; to no purpose.
The Century Dictionary and Cyclopedia
In an insignificant manner; without meaning; without importance or effect.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. in an insignificant manner
ad. not to a significant degree or amount
Word Usage
"A face that might be called insignificantly pretty and caressing manners thinly disguised the man's deeply-rooted egoism and habit of continually calculating the chances of a career which at that time looked problematical enough; though his choice of Mme. de"