Wiktionary
n. A number of uniform items which must be worn by pupils/students in a school.
Wikipedia
A school uniform is a uniform worn by students primarily for a school or otherwise educational institution. They are common in primary and secondary schools in various countries. Although often used interchangeably, there is an important distinction between dress codes and school uniforms: according to scholars such as Nathan Joseph, clothing can only be considered a uniform when it "(a) serves as a group emblem, (b) certifies an institution's legitimacy by revealing individual’s relative positions and (c) suppresses individuality." An example of a uniform would be requiring white button-downs and ties for boys and pleated skirts for girls, with both wearing blazers. A uniform can even be as simple as requiring collared shirts, or restricting colour choices and limiting items students are allowed to wear. A dress code, on the other hand, is much less restrictive, and focuses "on promoting modesty and discouraging anti-social fashion statements," according to Marian Wilde. Examples of a dress code would be not allowing ripped clothing, no logos or limiting the amount of skin that can be shown.
Usage examples of "school uniform".
One of them seemed to be wearing a school uniform: kneesocks and a short plaid skirt.
Marie, sitting quietly beside him in her school uniform (white scalloped blouse, pink pinafore, and white patent leather shoes), looked solemnly out the window at the flat green countryside.
Behind her came the son wearing a natty school uniform, who snapped to attention and saluted.
Ever since she had been a little girl she had wanted to wear a school uniform, and now, on assembly days, she really would.
Around each adult neck, a lanyard and whistle to supplement the earpiece and mic, and the assistant teachers woreas she didan adult version of the school uniform, white shirt and plaid slacks.
John was in a Probationer's school uniform, and Jeffrey was an obvious foreigner- an upper-class boy could go where he pleased, and the Fourth Bureau would be lethally interested if they heard of Prot6g6s talking to an auzlander.
Among them was a boy in a school uniform who was wounded in the head.
He found Fen, still dressed in her school uniform, slumped sobbing on the bed.
So I dug out an old school uniform--the only thing I could find that might fit him: he reeks of moth-balls, but he seems a little happier.
He still wore his black tunic, but with the addition of a short-billed black leather cap that she thought might have once been part of a school uniform.
There was a lighter mark on the cuffs of his school uniform jacket where the sleeves had been taken down, but even so his wrist-bones were visible.