Chino is a Spanish word. The term chinos, synonymous with khakis. These are cotton pants and were initially used as military uniforms in US and UK, imported from China. The fabric used in it was durable, very light and suitable for warm conditions.

  It was in 19th century khaki colour was famous and well accepted in US as it blended with the sand colour. Soon it became the staple for militants. As military uniforms they were straight fit, no pleats, tapered towards the bottom with buttons in front.
In 20th century American began to wear chinos, for semi-informal gatherings. Boys wore them to schools and colleges. By  1940s   it became associated with the preppy look. It was in 1950s chino banged up the market. The decline came by 1960 when jeans were preferred and more of casual style dressing took up the market. Still people did not stop wearing chino, though it became rare. Today its back in vogue, in a more stylized form worn informally. With brighter colours , pleats and other small detailing both for men and women. It need not be in 100% cotton, it has a little more of blended fabric for latest styling and fabric is not compulsorily from china. Basically it’s only the style as imitative of military uniform, rest all is modified.