Water retention, formally known as edema, is a symptom of a number of conditions including dehydration, constipation, hormonal changes, excess sodium in the diet, heart conditions and kidney problems.
dross. n. 1. Waste or impure matter: discarded the dross after recycling the wood pulp. 2. The scum that forms on the surface of molten metal as a result of oxidation. 3. Worthless, commonplace, or trivial matter: He was wide-awake and his mind worked clearly, purged of all dross (Vladimir Nabokov).
The definition of drowsy is  a feeling of being sleepy, tired or not fully awake. When you are just about to fall asleep and are having a hard time keeping your eyes open, this is an example of a time when you are drowsy.