The word 'pejorative' suggests negativity and is used to diminish the subject it describes. Referring to an old car as a 'hunk of junk' is pejorative.
Pro Tip 2/3
Cultural Sensitivity
Some words are pejorative in certain cultures but not in others. It's important to know the cultural context. The term 'gringo' can be pejorative in Latin American countries.
Pro Tip 3/3
Subjectivity
What is considered pejorative can vary from person to person based on personal feelings or beliefs. Calling someone 'thin' might be pejorative if it implies weakness.