Frequency: The word is one of the 1500 most common words in English.
Something that is ~ works well and produces the results that were intended.
The project looks at how we could be more ~ in encouraging students to enter teacher training...
Simple antibiotics are ~ against this organism...
...an ~ public transport system.
ADJ: oft ADJ in -ing, ADJ against n
...the team roles which you believe to be necessary for the team to function ~ly...
Services need to be more ~ly organised than they are at present.
ADV: usu ADV after v, also ADV -ed
...the ~ness of computers as an educational tool.
N-UNCOUNT: oft N of n
Effective means having a particular role or result in practice, though not officially or in theory.
They have had ~ control of the area since the security forces left.
ADJ: ADJ n
When something such as a law or an agreement becomes ~, it begins officially to apply or be valid.
The new rules will become ~ in the next few days.
ADJ: v-link ADJ