Improvised, or performed without preparation.

simple past tense and past participle of add up

Pertinent; relevant.

Pertinently; to the purpose.

plural of ad-lib

(law) The principle by which property rights extend vertically upwards and, sometimes, downwards from a property; it is used to describe air rights or no-fly zones, as well as rights to resources under the soil, such as mineral rights, among others.

For the purpose of a legal case, as in guardian ad litem.

Use of ad hoc or improvised reasoning. / (computing) Arbitrary decision rules sometimes included in artificially intelligent software to simulate the unexpectedness in human reasoning.

(Internet, advertising) An advertisement which extends horizontally across a web-page. / An advertisement on a banner.

Alternative spelling of ad hocery