1. past tense of sour; became acidic or spoiled
2. past tense of sour; became bitter or unpleasant in attitude

1. having become acidic, spoiled, or bitter

Examples

• The milk soured after sitting out all day.
• Their friendship soured after the argument.
• The soured cream had to be thrown away.
• His attitude soured when he didn’t get the promotion.
• The deal soured when new problems emerged.
• She threw out the soured yogurt.
• The relationship soured over money issues.