1.Definition: causing discomfort

"The unhappy truth"

2.Definition: 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"

3.Definition: generalized feeling of distress

Related Adjective(s):distressed, dysphoric

4.Definition: marked by or producing unhappiness

"Unhappy caravans, straggling afoot through swamps and canebrakes"

Related Adjective(s):infelicitous