1A sleep-inducing property or effect of a drug.
An explanation which merely restates in different (especially overly technical or abstract) words the very thing which is to be explained; a circular or tautological explanation.
virtus dormitiva/ˌvɪətʊs dɔːmɪˈtiːvə/ /ˌvəːtəs dɔːmɪˈtʌɪvə/
Mid 19th century. From post-classical Latin virtus dormitiva dormitive property from classical Latin virtus + post-classical Latin dormitiva, feminine of dormitivus.