itself
US /ɪtˈself/
UK /ɪtˈself/

1.
sí mismo, se
used as the object of a verb or preposition to refer to a thing, animal, or idea previously mentioned
:
•
The cat groomed itself.
El gato se acicaló a sí mismo.
•
The door closed by itself.
La puerta se cerró sola.
2.
en sí, mismo
used to emphasize the thing, animal, or idea mentioned
:
•
The city itself is beautiful, but the surrounding areas are not.
La ciudad en sí es hermosa, pero las áreas circundantes no lo son.
•
The problem itself is not that difficult.
El problema en sí no es tan difícil.