also: ウグイスあん
noun
sweet green pea paste; uguisu-an
A traditional Japanese sweet paste made from green peas, with a brownish-green color reminiscent of the Japanese bush warbler (uguisu). Used in wagashi.
うぐいす餡を使った和菓子は、春らしい色合いが人気です。
Wagashi made with uguisu-an are popular for their spring-like color.
この大福にはうぐいす餡が入っています。
This daifuku contains uguisu-an.
From うぐいす (Japanese bush warbler) + 餡 (sweet bean paste), named for the bird's olive-green color which the paste resembles.