TrialOrder = randperm(Number_of_elements, Number_to_select)
Words(TrialOrder)
This applies provided that each element is to be selected at most once (selection without replacement). If you are trying to randomize the order of presentation of words in which each word is to occur exactly the same number of times over the whole sequence, then you would use different code that would depend on the rules about how soon the same word can reappear.
