These are common terminology in Forth and other computer languages with a stack.

peek or tos
Examine top of stack. (... x y tos gives you y and keeps the stack)
Add element to top of stack; other elements are pushed down. (... x push y makes the stack ... x y)
Remove element from top of stack. ( ... x y pop makes the stack ... x)
Swap top two stack elements. (... x y swap makes the stack ... y x)
"Rotate" top 3 elements, bringing third element to top of stack. (... x y z rot makes the stack ... y z x)
"Rotate" top 3 elements in other direction. (... x y z unrot makes the stack ... z x y)
Duplicate top stack element. (... x dup makes the stack ... x x)
Duplicate second stack element over top of stack. (... x y over makes the stack ... x y x; equivalent to swap dup unrot)
nip, tuck, pick, ...
Over the years, Forth programmers invented many more useful operations!

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