vanilla: [17] A vanilla pod is etymologically a ‘little vagina’. The word was borrowed from Spanish vainilla, a diminutive form of vaina ‘sheath’ (the pod was so named because of its sheath-like shape). Vaina was descended from Latin vāgīna ‘sheath’, which came to be jokingly applied to the ‘female reproductive passage’ – hence English vagina [17]. => vagina[vanilla etymology, vanilla origin, 英语词源]