Try using it this way:

var getRandomWord = (function () {
  var gameWordArray = [];
  gameWordArray.push("monitor");
  gameWordArray.push("program");
  gameWordArray.push("application");
  gameWordArray.push("keyboard");
  gameWordArray.push("javascript");
  gameWordArray.push("gaming");
  gameWordArray.push("network");
  return function () {
    var randNum, finalWord;
    randNum = Math.floor(Math.random() * gameWordArray.length);
    finalWord = gameWordArray[randNum];
    return finalWord;
  };
})();

DEMO: http://jsfiddle.net/bCEFA/1/

Instead of declaring an array with a predefined length, you might as well declare an empty one and add values to the end of it (with .push()). You could've also declared the array like:

var gameWordArray = ["monitor", "program", ...];

You were trying to print word (which I renamed to getRandomWord), which was/is a function. You probably meant to use console.log(gameWordArray[randno]), which should work.

This is a functional approach. First call you pass the target array to choose items from, then the next call is the amount.

const numbers = ['1', '2', '3', '4', '5', '6', '7', '8', '9', '0'];

const words = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'k'];

function randomNum(target) {
  const newRandomNum = (num = 1, val = "") => {
    val += (target[Math.floor(Math.random() * 9)])
    if (num === 1) return val;
    return newRandomNum(--num, val);
  }
  return newRandomNum;
}

console.log(randomNum(numbers)(5));
console.log(randomNum(numbers)(10));

console.log(randomNum(words)(5));
console.log(randomNum(words)(10));

An improvement you could make is to check the type of the target array, then use += for strings, and another method for numbers since you don't want to add them.

You can use Math.random() to get a random number beteween 0 and 1.

If you want a whole random number between 0 and 2. (so: 0, 1 or 2). You can use:

Math.floor(Math.random()*3);

Note that Math.round (instead of floor) would be wrong here since the edge values will have a lower chance, and you might actually get 3 as well.

you can simply shuffle your array

const words = 
  [ 'monitor', 'program', 'application', 'keyboard'
  , 'javascript', 'gaming', 'network'
  ]
for (let i = words.length; --i;)  // shuffle Array
  {
  let j = Math.floor(Math.random() * (i + 1));
  [words[i], words[j]] = [words[j], words[i]]
  }

// get 2 random words
console.log( words[0], words[1] )

Why not Mapping it first and then Apply your call?

// Example: 
const requiredLength = 5,
const originalArr = ['lalal', 'hehehehehe', 'uhuhuhuh', 'uooou'];

const arr = originalArr.map(word => word.length === requiredLength);
// arr = ['lalal','uooou'];

const word = arr[Math.floor(Math.random()*arr.length)];

If you've already got underscore or lodash included in your project you can use _.sample.

// will return one item randomly from the array
_.sample(['January', 'February', 'March']);

If you need to get more than one item randomly, you can pass that as a second argument in underscore:

// will return two items randomly from the array using underscore
_.sample(['January', 'February', 'March'], 2);

or use the _.sampleSize method in lodash:

// will return two items randomly from the array using lodash
_.sampleSize(['January', 'February', 'March'], 2);

Yes, use an array. To get a random word from such an array, use the following:

function getRandomWord() {
   var words = ['Apple','Banana','The','Orange','House','Boat','Lake','Car','And'];
   return words[Math.floor(Math.random() * words.length)];
}

Then invoke that function to whatever extent you like.

var paragraph = [];
for(var i = 0; i < 50; i++)
    paragraph.push(getRandomWord());

$('#my-container').text( paragraph.join(' ') );