Breakdown of Eu não acredito nessa superstição.
eu
I
não
not / no
em
in / on / at
esse
that (esse, essa, esses, essas)
Questions & Answers about Eu não acredito nessa superstição.
Why does the sentence use nessa instead of just essa?
The verb acreditar (to believe) is followed by the preposition em (in). When em meets the demonstrative pronoun essa (that), they merge into the contraction nessa (in that).
How do I know whether to use nessa, nesta, or naquela?
You use nessa when the superstition is associated with the person you are talking to, or was just mentioned by them. If it was a belief that you just brought up yourself, you would use nesta (in this). If it was a distant or historical belief, you would use naquela (in that one over there).
How can I easily tell that superstição is a feminine word?
As a very reliable rule in Portuguese, words ending in -ção are almost always feminine. Because of this, it must be paired with the feminine contraction nessa rather than the masculine nesse.