The rank of a noun is the count of its axes. An atom has rank 0, a list rank 1, a table rank 2, and an array with 5 axes has rank 5. The rank of an array is very important and determines in a significant way how verbs act upon it.
The shape of an array is a list with as many numbers as the array has axes. This means that the count of the shape of an array is the rank of the array.
# $ 4 NB. atom has rank 0 0 # $ 4 5 6 NB. list has rank 1 1 # $ 2 3 $ 'a' NB. table has rank 2 2