misery/ 'mɪzərɪ /

1.noun [u] 
(unhappiness) 痛苦

2.noun [u] 
(wretchedness) 穷困

3.noun [c] [esp BRIT] [inf] 
(person) 爱发牢骚的人

to put sb out of their misery
 [inf] 解开某人心中的疑团
to put sth out of its misery
杀死某动物以结束其痛苦
to make sb's life a misery
使某人日子不好过