A cultivar, short for "cultivated variety," is a genetically distinctive variety of a cultivated plant species. In homebrewing, cultivars are one way in which hop varieties are distinguished from each other.
However, not every hop variety is a true cultivar; genetically identical plants grown in different regions can have very different character and be sold under very different names. For example, the hop variety sold as American Tettnanger is not the same cultivar as German Tettnanger hops; it is in fact genetically similar or identical to English Fuggle.
For more information on the way hop varieties are distinguished from each other, see the main article on hop varieties.