premise: convulsive <mask>; a twitch in the side
hypothesis: the best context for <mask> here is The relaxation of a law in a particular case; permission to do something forbidden, or to omit doing something enjoined; specifically, in the Roman Catholic Church, exemption from some ecclesiastical law or obligation to God which a man has incurred of his own free will (oaths, vows, etc.).; but not A short, spastic contraction of the fibers or muscles; a simple muscular contraction.