English definition of “itself”
REFLEXIVE › the reflexive form of the pronoun 'it': The cat licked itself clean.
EMPHASIS › used to emphasize the particular thing you are referring to: The garden is enormous but the house itself is very small.
(all) by itself › alone: The dog was in the house by itself for several days. › automatically: The heating comes on by itself.
in itself › as the only thing being talked about and nothing else: You've managed to complete the course - that in itself is an achievement.