sour/ 'sauər /

1.adjective
(bitter-tasting) 酸的

2.adjective [+milk] 
酸的

3.adjective
(bad-tempered) 愠怒的

4.vt.[+relationship] [ attitude] 
使恶化

5.vi.[relationship] [ attitude+] 
变坏

to go {or} turn sour
 [milk,wine+] 变馊
6.vi.[relationship+] 
变糟

it's sour grapes
这是酸葡萄