statistics

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The mathematics of the collection, organization, and interpretation of numerical data, especially the analysis of population characteristics by inference from sampling.
• noun Numerical data.

from The Century Dictionary.

• noun A systematic collection of numbers relating to the enumeration of great classes, or to ratios of quantities connected with such classes, and ascertained by direct enumeration.
• noun The study of any subject, especially sociology, by means of extensive enumerations; the science of human society, so far as deduced from enumerations.

from the GNU version of the Collaborative International Dictionary of English.

• noun The science which has to do with the collection, classification, and analysis of facts of a numerical nature regarding any topic.
• noun Classified facts of a numerical nature regarding any topic.
• noun Numerical facts respecting the condition of the people in a state, their health, their longevity, domestic economy, arts, property, and political strength, their resources, the state of the country, etc., or respecting any particular class or interest; especially, those facts which can be stated in numbers, or in tables of numbers, or in any tabular and classified arrangement.
• noun (Sport) Numerical facts regarding the performance of athletes or athletic teams, such as winning percentages, numbers of games won or lost in a season, batting averages (for baseball players), total yards gained (for football players). The creation and classification of such numbers is limited only by the imagination of those wishing to describe athletic performance numerically.
• noun The branch of mathematics which studies methods for the calculation of probabilities.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A mathematical science concerned with data collection, presentation, analysis, and interpretation.
• noun A systematic collection of data on measurements or observations, often related to demographic information such as population counts, incomes, population counts at different ages, etc.
• noun Plural form of statistic.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a branch of applied mathematics concerned with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters