I used to interpret viññāṇa to mean consciousness as basic awareness of something. But I am not sure that the pali term is so basic.
In VsM it says that viññāṇa knows more than saññā, thus to me it is more complex than simply being aware:
Perception is like the child without discretion seeing the coin, because it apprehends the mere mode of appearance of the object as blue and so on. Consciousness is like the villager seeing the coin, because it apprehends, the mode of the object as blue, etc., and because it extends further, reaching the penetration of its characteristics. Understanding is like the money changer seeing the coin, because, after apprehending the mode of the object as blue, etc., and extending to the penetration of the characteristics, it extends still further, reaching the manifestation of the path. VsM XIV,5
Also viññāṇa seems to be made of two words vi + ñāṇa.
Vi can mean: special, separate, apart, free from, clear, different.
ñāṇa means knowledge.
Apparently one of the translations of viññāṇa is discernment
I've read somewhere that viññāṇa can mean something like (duality) separation between sense organ and sense objects.