noun
azure-winged magpie
A bird species (Cyanopica cyanus) found in East Asia. In Japanese, the name is almost always written in katakana.
公園でオナガを見かけました。
I saw an azure-winged magpie in the park.
prefix
long-tailed
Prefix used in animal names to indicate a long tail, e.g., オナガドリ (long-tailed fowl). Not freely productive.
オナガドリは尾羽がとても長い鳥です。
The onagadori is a bird with very long tail feathers.
From 尾 (o, 'tail') + 長 (naga, 'long'). The bird name derives from its notably long tail.