The word efficacious means about the same as "effective" -- it means capable of having the intended result.
Example:
"A shotgun is efficacious in controlling wild rabbits."
"For a simple cough, honey is often as efficacious as medicinal syrups."
Effectiveness.
That medicine is efficacious in treating a cold
Effective, effectual, efficacious, productive, industrious.
(Capable of having a desired effect or result, effective.)"The medicine is efficacious in stopping a cough.""The farmers were looking for a chemical that would be efficacious against the corn fungus."
productive, efficient, effective
Quinine
An efficacious symbol is something that promotes an idea, but at the same time it actually causes that idea to happen. For example, the Church is one because it "promotes" salvation, but it also "causes" salvation.
Useful, of course, but also handy, utile, efficacious, productive
successful, efficacious, useful
B12
Efficacious signs of grace refer to sacraments in the Catholic Church, through which believers receive God's grace. The sacraments are considered effective and powerful channels of divine grace, bringing about what they symbolize. Each sacrament is believed to confer specific graces that help believers grow in their faith and relationship with God.
efficacious - having strong swaying power or hindering the the behaviors of others.
The Three definitions are: Mystery: DOES NOT mean something to solve. It is a religious truth that one can experience but cannot fully understand. It is a visible GRACE of an invisible REALITY An efficacious sign of grace instituted by Christ and entrusted to the Church by which the Divine Life is dispensed Efficacious--It causes what it symbolizes and accomplishes what it represents. It points to something that is far beyond it, but that is closely related. An outward or visible sign that is instituted by Christ.