This is the 602nd most frequent Catalan word.
particular
"Particular" in Catalan means "private" or "specific."
Here, 'particular' is used as an adjective meaning 'private', to describe a tutor who gives individualized lessons.
Tinc un professor particular que m'ensenya matemàtiques.
I have a private tutor teaching me mathematics.
In this case, 'particular' refers to 'specific' or 'distinct,' qualifying the type of interest mentioned.
Va mostrar un interès particular en la història de la ciutat.
He showed a particular interest in the history of the city.
Here 'particularment' (adverbial form of 'particular') means 'especially,' emphasizing the interest level of the design.