agnus castus
/ˈaɡnəs ˈkastəs/noun
1An aromatic shrub, Vitex agnus-castus (family Verbenaceae), native to the Mediterranean and central Asia, which has digitate leaves, tall spikes of lilac-coloured flowers, and small round reddish-black berries; also called chaste tree. Formerly also: †the plant tutsan, Hypericum androsaemum (family Hypericaceae), with reddish leaves and yellow flowers ( obsolete ).
2Any of various medicinal preparations made from the seeds, fruits, or other parts of Vitex agnus-castus, formally believed to reduce sexual potency or desire, and now used mainly in herbal remedies for menstrual and menopausal symptoms.
Origin
Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. From post-classical Latin agnus castus from agnus + classical Latin castus chaste.