I was searching on the meaning of skirt in Longman dictionary and I found the definition which is: “a piece of outer clothing worn by women and girls”, Why did not he say: “a piece of outer clothing is worn by women and girls”, Why did they not use an auxiliary verb?
Answer
“a piece of outer clothing worn by women and girls” is not a complete sentence.
In a sentence it would be:
A skirt is a piece of outer clothing worn by women and girls
Past participles can be used together with an auxiliary verb to form a sentence or without one and then they act as adjectives.
It’s the same as saying:
a piece of outer clothing that is worn by women and girls
Attribution
Source : Link , Question Author : Mohammad Alshareef , Answer Author : Martin W