noun
three-day journey
A journey or distance that takes three days. Often used in classical or poetic contexts, but still understandable in modern Japanese.
ここから京都までは三日路だ。
It's a three-day journey from here to Kyoto.
二日路 means a two-day journey, while 三日路 specifically refers to a three-day journey.
Compound of 三日 (みっか, 'three days') and 路 (じ, 'road' or 'journey'). The reading みっかじ follows regular rendaku voicing of ち to じ.