sed·a·tive (sěd'ə-tĭv) adj. Having a soothing, calming, or tranquilizing effect; reducing or relieving anxiety, stress, irritability, or excitement. n. An agent or a drug having a soothing, calming, or tranquilizing effect.
[Middle English, from Old French sedatif, from Medieval Latin sēdātīvus, from Latin sēdātus, past participle of sēdāre, to calm; see sedate1.]
"tending to calm or soothe," c.1425, from M.L. sedativus "calming, allaying," from pp. stem of sedare (see sedate). The noun derivative meaning "a sedative drug" is attested from 1785.
sedative sed·a·tive (sěd'ə-tĭv) adj. Having a soothing, calming, or tranquilizing effect; reducing or relieving anxiety, stress, irritability, or excitement. n. An agent or a drug that produces a soothing, calming, or tranquilizing effect.