noun
spring overcoat
Rare term for a lightweight overcoat worn in spring.
春外套は、春先の肌寒い日に羽織るのにちょうどいい。
A spring overcoat is just right for throwing on during chilly early spring days.
外套 is a somewhat literary or old-fashioned word for overcoat; 春外套 adds the seasonal specification.
Compound of 春 (spring) and 外套 (overcoat). The exact historical derivation is uncertain, but the word is a straightforward seasonal compound.