When we change compound nouns into their plural forms, there are some general guidelines that we can follow for each category. That said, it is always wise to consult a dictionary when using these nouns; there are many exceptions to the general rules outlined here!
Noun + Adjective
In these cases, both words comprising the compound noun are pluralized.| la terracotta ... le terrecotte la cassaforte ... le casseforti il caposaldo ... i capisaldi la cartastraccia ... le cartestracce |