'high-grade' originates from the combination of 'high' and 'grade', where 'high' meant 'great in amount, size, or degree' and 'grade' meant 'a particular level of quality'.

'high-grade' evolved from the combination of the Old English word 'hēah' (high) and the Latin word 'gradus' (grade), eventually becoming the modern English term 'high-grade'.

Initially, it meant 'of a high level or degree', and this meaning has largely remained the same in modern usage.