Before looking at the dictionary proper definition of “quality”, let me try to answer it naively. So, according to djitz (that’s me):
Quality is a trait of an object that is subjective to different person.
For more formal definition, you can follow this link to Merriam-Webster definition of “quality”.
The first part of my definition doesn’t seem to be that much different from the dictionary definition, however I think the “subjectivity” part is important.
Because quality, just as it’s cousin, beauty, is in the eye (and mind) of the beholder.
There’s always different groups that side to certain products, just take a look at iOS vs Android, Windows vs Mac (or Windows vs Linux), Canon vs Nikon, the list can go on and on..
What causes this division? Obviously because different group of people prefer different quality from certain products.
The division doesn’t always come in two major groups, it can come in more distributed manner. Just take a look at the product reviews in Amazon.com. Although the peer reviews are helpful in determining a quality of the product, in most cases it can also confuses people. It’s not unusual to see a five star rated product review followed by a one star rated one.
So, just to sum it up, quality is people’s relative perception of an object.