A little playful XQuery

antonyms-game.xqy

xquery version "3.1";

declare function local:lookup-word($word as xs:string, $request as xs:string, $id as xs:string, $key as xs:string) {
  let $request :=
    <http:request href="https://od-api.oxforddictionaries.com/api/v1/entries/en/{$word}/{$request}"  method="get">
      <http:header name="app_key" value="{$key}"/>
      <http:header name="app_id" value="{$id}"/>
    </http:request>
  return http:send-request($request)
};

let $phrase := "I feel excited!"
for $word in fn:tokenize($phrase, "\W")
let $request := "antonyms"
let $id := "###"
let $key := "###"
let $lookup-word := local:lookup-word(?, ?, $id, $key)
let $entry := $lookup-word($word, $request)
let $senses := $entry//senses/_/antonyms/_/text/text()
let $count := fn:count($senses)
return 
  if ($count > 0) then
    let $rnd := random:integer(fn:count($senses)) + 1
    return $senses[$rnd]
  else
     $word