1. (

• correlation ,
• correlativity

) a reciprocal relation between two or more things ;

2. (

• correlation_coefficient ,
• coefficient_of_correlation ,
• correlation

) a statistic representing how closely two variables co-vary; it can vary from -1 (perfect negative correlation) through 0 (no correlation) to +1 (perfect positive correlation); "what is the correlation between those two variables?" ;

3. (

• correlation ,
• correlational_statistics

) a statistical relation between two or more variables such that systematic changes in the value of one variable are accompanied by systematic changes in the other ;