noun
local road; non-highway road; toll-free road
Refers to ordinary roads that are not expressways or toll roads. Often used in contrast with 高速道路 (expressway).
高速を使わずに下道で行くほうが安い。
It's cheaper to take local roads instead of the expressway.
この先は下道が混んでいるので、高速
The local roads are congested ahead, so let's get on the expressway.
noun
road shaded by trees or mountains
Describes a road that is shadowed or darkened by overhanging trees, mountains, or other natural features. Less common than sense 1.
山あいの下道は昼でも薄暗い。
The road shadowed by the mountains is dim even during the day.
Compound of 下 (shita, 'below' or 'lower') and 道 (michi, 'road'). The exact historical derivation is uncertain; the spelling is conventionally associated with the meanings 'local road' and 'shaded road'.