Meaning and Usage
The adjective 深い (ふかい) primarily means "deep" in a physical sense, such as depth of water or a hole. It also extends metaphorically to describe abstract concepts like profound thoughts, deep feelings, or intense states.
Common Collocations
- 深い川 (ふかいかわ): a deep river — used literally for physical depth.
- 深い考え (ふかいかんがえ): profound thought — used to describe complex or serious thinking.
- 深い眠り (ふかいねむり): deep sleep — refers to a state of restful, uninterrupted sleep.
Usage Notes
When using 深い to describe physical depth, it often implies a measurable or noticeable extent downward or inward. For abstract uses, it conveys seriousness, intensity, or complexity.
Be careful not to confuse 深い with 高い (たかい, "high") when describing vertical dimensions; 深い is for depth downward, 高い is for height upward.
Register and Politeness
深い is a common adjective used in both casual and formal contexts without change in form. It is neutral in politeness and can be used in everyday conversation as well as written language.