Cashews are often referred to as a nut, but botanically they are classed as a seed, as they come from the cashew fruit (which is also known as a drupe). Drupes are fruits that are fleshy on the outside, but contain a shell with a seed on the inside. Cashew plants belong to a group of plants known as anacardiaceae, which includes mango, sumac and poison ivy. https://globalbusinessltd.co.uk/product/cashew-nuts/