Return ordered combinations of letters

Question

I'm trying to write a function that returns:

['cat', 'cot', 'cut']

When passed this list:

['c', 'aou', 't']

But would also return:

['cats', 'catz', 'cots', 'cotz', 'cuts', 'cutz']

When passed:

['c', 'aou', 't', 'sz']