Binding and Loosing
The power promised by Christ to the rulers of His Church when He said to the Apostles:
"Whatsoever you shall bind upon earth, shall be bound also in heaven; and whatsoever you shall loose upon earth, shall be loosed also in heaven" (Matthew 18; cf. 16).
Whatever be the primary signification of this metaphor in the Aramaic language, these words as used by Christ, as is evident from the context and from Christian tradition, meant that He was to confer upon the rulers of His Church the power to bind the faithful to the observance of laws and to loose them from impediments to eternal happiness, especially from sin and its consequent debt of punishment.
New Catholic Dictionary