Colloquially, it can be used to express "very" or "quite." It is also more natural sounding to use 정말.
참 is more like "so much" or "that". Like for example: 그 남자는 정말 참 나쁩니까? - Is that man really that bad?
On the other hand 매우 is pretty much the same as 아주, both mean 'very'. Though 아주 is less used.