1.
dream (during sleep)
A series of images and sensations during sleep.
2.
dream, aspiration
A hope or ambition for the future.
夢 has two meanings: dreams during sleep and aspirations/ambitions.
SLEEP DREAMS:
- 夢を見る: to have a dream (NOT 夢がある)
- 悪夢: nightmare
- 夢の中で: in a dream
ASPIRATIONS:
- 夢がある: to have a dream/goal
- 夢が叶う: dream comes true
- 夢を諦める: to give up on a dream
- 夢を追いかける: to chase a dream
COMPOUNDS:
- 夢中: absorbed, engrossed
- 白昼夢: daydream
- 初夢: first dream of the new year
IDIOM:
夢のよう: dreamlike, too good to be true