A measure of the effectiveness of something.(noun)
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Use "effectivity" in a sentence
"Tuesday I will be at the effectivity training again, probably telling the trainer that I got some great results and I don't know how."
"On the menu this week: another day of the personal effectivity training tomorrow, and then some D&D to finish the day off."
"Work got me a little stressed; my department manager and I had a talk about me and and how I'm doing and he thinks I need some serious personal effectivity training to learn to be assertive and take initiative."