The Koren Sacks Siddur is a prayer book that features a unique translation and commentary by Rabbi Jonathan Sacks. However, there are various synonyms that can also be used to refer to it. Some of these include the "Koren Siddur," "Koren Sacks Prayer Book," "Siddur Koren," and the "Koren Sacks Edition of the Siddur." Additionally, other terms like "prayer book," "prayer guide," and "book of prayers" can be used to refer to a similar type of book. Regardless of what term is used, the Koren Sacks Siddur remains a popular prayer book among Jews worldwide.