associativity
How many slots each group in a cache has, so how many lines with the same index can be kept at once: 1 for direct-mapped, 8 for an 8-way cache.
Associativity N is the number of ways per set; N = 1 is direct-mapped and N = number of lines is fully associative. Higher associativity removes conflict misses at the cost of more tag comparisons per lookup.