- 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, "", 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.
- French: efficacité
- German: Wirksamkeit, Effektivität
- Italian: efficacia
- Portuguese: eficiência
- Russian: эффекти́вность
- Spanish: efectividad
- Spanish: eficacia