continuous rain; steady rain
Refers to rain that falls steadily over a wide area for a long period, as opposed to localized showers. Often used in weather forecasts.
明日は地雨が降り続くでしょう。
Tomorrow, steady rain will continue to fall.
地雨のため、傘が手放せない一日だった。
Because of the continuous rain, it was a day I couldn't be without an umbrella.
Compound of 地 (ji, 'ground' or 'earth') and 雨 (ame, 'rain'), suggesting rain that soaks the ground steadily. The exact historical derivation is uncertain.