reps = {'1/2': 'half', '1/4': 'quarter', '3/4': 'three quarters'}
li = ['I own 1/2 bottle', 'Give me 3/4 of the profit']
map(lambda s: ' '.join([reps.get(w, w) for w in s.split()]), li)
Applying a dictionary of string replacements to a list of strings