ARM, in Geography, is used for the branch of a sea or river. Italy and Sicily are only parted by an arm of the sea. St George's arm is the Mediterranean is the Thracian Bosphorus.
ARM is also used figuratively for power. The secular arm is the lay or temporal authority of a secular judge; to which recourse is had for the execution of the sentences passed by ecclesiastical judges.
The church sheds no blood: even the judges of the inquisition, after they have found the person guilty, surrender him to the secular arm. The council of Antioch, held in 341, decrees, that recourse be had to the secular arm to repress those who refuse obedience to the church: for secular arm, they here use exterior power.