The root of kausheya is kosha or kausha. It means – among other ones – the sheath covering the silk worm. This is nothing but the 'pupa'. The pupa is called kausha or kOsha.
The derived meaning of the term kausheya is 'cloth made from the cocoon shell'
however in Ramayana; Ma Sita wears two kinds of silk , one Kausheya and another made from 'Shalmali' tree which usually is known as Cotton-silk ; It used to be of the color 'Ochry '