noun
garden stream; narrow stream in a traditional Japanese garden
Refers to a small, often artificial stream in a Japanese garden, especially associated with Heian-period shinden-zukuri architecture.
See also: 寝殿造り
寝殿造りの庭には、遣り水が流れていた。
A garden stream flowed through the shinden-zukuri style garden.
noun
watering plants; watering potted plants or bonsai
Used for the act of watering plants, especially potted plants or bonsai. Less common than 水やり in everyday speech.
盆栽の遣り水は、朝早くが良い。
It's best to water bonsai early in the morning.
More common and general term for watering plants; 遣り水 is more specific to potted plants or bonsai and can sound slightly traditional.
Compound of 遣り (yari, continuative form of 遣る 'to do, send') + 水 (mizu 'water'). The garden stream sense is old, dating back to Heian-period garden design.