import re
words = ["THIS", "THAT"]
sentences = ["I want to identify THIS word.", "And THAT!", "But I do not want to identify !THIS word", "Or [THIS] word"] 

pattern = fr"(?<!\S)(?:{'|'.join(words)})\b"
for sentence in sentences:
	word_re = re.search(pattern, sentence) 
	if word_re:
		print(f"'{sentence}' is a match!")