efficacious
adjective uk/ˌef.ɪˈkeɪ.ʃəs/ us/ˌef.əˈkeɪ.ʃəs/
formal灵验的；奏效的；有效的
able to produce the intended result
We believe that educational or counselling schemes are a more efficacious way of dealing with this problem than harsh sanctions.
Synonym: effective (SUCCESSFUL)