reverse

From The K Language Wiki
Reverse
|x

reverse reverses the order of items in a list or the order of records in a table. It has no effect on atoms. For a dictionary, it reverses both the keys and the values.

 |"abc"
"cba"
 |+`a`b!(0 1;2 3)
`a`b!(1 0;3 2)
 |12
12
 |`a`b!0 1
`b`a!1 0