This is the 11252nd most frequent Portuguese word.
mentirosa
"Liarm"
In this sentence, 'mentirosa' is used as a noun to describe someone who lies habitually.
Ela é uma mentirosa, nunca diz a verdade.
She is a liar, she never tells the truth.
Here, 'mentirosa' acts as an adjective to qualify the story as deceitful.
Essa história é tão mentirosa que ninguém acreditou.
This story is so deceitful that nobody believed it.
In this instance, 'mentirosa' refers to behavior and is used as a noun in an imperative sentence addressing someone directly.