import re
s = 'python xyx 234 aa4!@!4XY. paaAyyy984a ABCa-xYxx3yYa java aa.'
pattern = r'\w+a\b' # words ends with 'a'
for match in re.findall(pattern, s):
print('Found: {!r}'.format(match))
'''
run:
Found: 'paaAyyy984a'
Found: 'ABCa'
Found: 'xYxx3yYa'
Found: 'java'
Found: 'aa'
'''