Noun

(-)

The property of being effective, of achieving results.

The effectiveness of the drug was well established.

The capacity or potential for achieving results.

*

The degree to which something achieves results.

He questioned the effectiveness of the treatment.

* 2013 , Phil McNulty, "[http://www.bbc.co.uk/sport/0/football/23830980]", BBC Sport , 1 September 2013:

United were having more possession but a sign of the effectiveness of Liverpool's defence was that it took the visitors 76 minutes to force Mignolet into serious action, when he dived to punch away a shot from substitute Nani.

Noun

(uncountable) Inadequacy or incompleteness.

* {{quote-book, year=1963, author=(Margery Allingham), title=(The China Governess)

, chapter=17 citation , passage=The face which emerged was not reassuring. […]. He was not a mongol but there was a deficiency of a sort there, and it was not made more pretty by a latter-day hair cut which involved eccentrically long elf-locks and oiled black curls.}}

(countable) An insufficiency, especially of something essential to health.

* {{quote-magazine, date=2013-08-31, volume=408, issue=8851, magazine=(The Economist)

, title= Promotion and self-promotion , passage=One of academia’s deficiencies is that, though its lecture halls and graduate schools are replete with women, its higher echelons are not. Often, this is seen as a phenomenon specific to the sciences. … In fact, the disparity applies to the whole grove. Another report from 2006, by the American Association of University Professors, found the same ratio in the faculties of arts, humanities and social science, too.}}

(geometry) The amount by which the number of double points on a curve is short of the maximum for curves of the same degree.

(geometry) The codimension of a linear system in the corresponding complete linear system.