Thanks for the advice Wolfgang.
I went back to the wiki and found \setupfootnotes, \placefootnotes and \setupfootnotedefinition.  Playing around with these I almost get what I want.  What I don't get is two way interaction i.e. clicking on the superscript in the text doesn't take me to the footnote (or endnote in this case), but clicking on the superscript of the footnote takes me back to the word in the text.  I would really prefer to be able to click on a word to take me to the definition and click on the definition to take me back to the word.