The adj unhappy has 4 senses (first 2 from tagged texts)
1. (6) unhappy -- (experiencing or marked by or causing sadness or sorrow or discontent; "unhappy over her departure"; "unhappy with her raise"; "after the argument they lapsed into an unhappy silence"; "had an unhappy time at school"; "the unhappy (or sad) news"; "he looks so sad")
2. (1) dysphoric, distressed, unhappy -- (generalized feeling of distress)
3. unhappy -- (causing discomfort; "the unhappy truth")
4. infelicitous, unhappy -- (marked by or producing unhappiness; "infelicitous circumstances"; "unhappy caravans, straggling afoot through swamps and canebrakes"- American Guide Series)