import re
strings = ['corpus christi tx', 'san angelo', 'oklahoma city ok', 'abilenesweetwater']
lookup = {'tx': 'texas', 'ny': 'new york', 'nj': 'new jersey', 'ok': 'oklahoma'}
rx =  re.compile(fr'\b(?:{"|".join([key for key in lookup])})\b')
strings = [rx.sub(lambda x: lookup[x.group()], s) for s in strings]
print(strings)