plurality is implicit in the word "array" or the symbol @

Untrue. It denotes listishness. (For the purpose of argument, I consider an array to be a very special type of list.) Consider a single element array slice -- not plural, but still a list:

my @time;
@time[0] = localtime;
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That's a rather useless snippet of code, but it demonstrates the point.

Update: The naming suggestions make sense, and will make even more sense in Perl 6.