In programming languages, a keyword is a predefined, reserved word with special meaning to the compiler. Keywords are part of the syntax of a language and cannot be used as identifiers, like int in C.
Hoon uses runes for its basic operators, so it does not have any reserved alphanumeric keywords. Additionally, while there are many function names in the standard library, these can all be shadowed (though this is not always a good idea from a readability perspective).