Slice/slaɪs/ Definition 1 of 6Pro Tip 1/2Quantity Varies The size of a 'slice' can vary greatly depending on who cuts it and what food is sliced. He cut a huge slice of pizza, much bigger than the rest. Pro Tip 2/2Culinary Terms 'Slice' is often used in recipes and cooking to provide instructions on preparing food. Slice the tomatoes thinly and spread them on the bread.