SARDONIUS risus, Sardonian laughter. A convulsive involuntary laughter; thus named from the herba sardonis, which is a species of ranunculus, and is said to produce such convulsive motions in the cheeks as resemble those motions which are observed in the face during a fit of laughter. This complaint is sometimes speedily fatal. If the ranunculus happens to be the cause, the cure must be attempted by means of a vomit, and frequent draughts of hydro-mel with milk.