Latin efficāx

→ English efficacy (mention)

→ English efficacious (derived)

→ French efficace (mention)

→ Indonesian efikasi (mention)

→ Italian efficace (mention)

→ Latin efficacitas (affix)

→ Latin efficaciter (suffix)

→ Latin inefficax (affix)

→ Norman êfficace (mention)

→ Romanian eficace (borrowed)