Used before a noun to mean 'the part of your life when you are awake, not asleep'. You will almost always see it in the phrase every waking hour or every waking moment, and the point of the phrase is that something fills all of your time: She spends every waking hour studying means from the second she opens her eyes to the second she falls asleep, that is what she is doing. It usually carries a slight feeling of too much — of someone giving more to a thing than is healthy. There is a second, quieter use: waking life, waking hours, waking thoughts, meaning the ordinary daytime world as opposed to dreams. In waking life he was a shy man means when he was not dreaming. Note that waking is also just the -ing form of the verb wake (Waking him is impossible), but that is a different job; here it is describing the noun after it.