That would be a hash. Arrays are indexed numerically.

From perldata :

Perl has three data structures: scalars, arrays of scalars, and associative arrays of scalars, known as ``hashes''. Normal arrays are indexed by number, starting with 0. (Negative subscripts count from the end.) Hash arrays are indexed by string.

The only gotcha I can think of is that hashes aren't stored 'in order' -- perl will store hash elements in a seemingly random fashion, but that's what sort keys %hash is for.