The Chinese word for watermelon is
西瓜

xī guā

Chinese Definition

watermelon
1. 西瓜
Components
西
1. west; western
2. (Cantonese, euphemistic) Synonym of 閪 (hai1)
3. spin (noun)
腳趾尾mei5-1 拉laai1西 - to do a sidespin with one's little toe -
4. to spin; to cause to spin
5. carrying spin
6. to deviate from a path due to some force
架車轉zyun3彎嗰陣zan6-2 好西。 - There was strong centrifugal force when the vehicle turned.
7. to hit
一嘢西落佢度
瓜
1. melon; gourd; squash
西瓜 - watermelon
南瓜 - pumpkin
冬瓜 - winter melon
2. (Cantonese, slang) to die
3. (Mainland, slang) storyful news
今年最大的瓜 - the most storyful news this year
4. (Singapore, colloquial) fellow; dude