a light sleevelesscoat of chain mail worn under the hauberk
鎖帷子の下に着る袖無しの軽量よろい - 日本語WordNet
a short sleeveless outer tunic emblazoned with a coat of arms
紋章で飾られた短いアウター用のチュニック - 日本語WordNet
a man's sleeveless garment worn underneath a coat コートの下に着られる男性のそでなしの衣服 - 日本語WordNet
a sleevelesscoat that is a folk costume of South Americans, called poncho
南米人の民族衣装でポンチョという袖なしの外衣 - EDR日英対訳辞書
As for the origins of the name, some insist that Jinbei is short for 'Jinbei-haori,' informal summer clothes worn by a man called Jinbei, but the more prevailing theory is that 'Sodenashi-baori' (sleeveless coat) worn by commoners at the end of the Edo period resembled 'warriors' Jinbaori' (sleeveless campaign jacket worn over armor) in shape.
甚平は「甚兵衛羽織」の略で「甚兵衛という名の人が着ていたことから」という起源説もあるが、江戸時代末期に庶民が着た「袖無し羽織(そでなしばおり)」が、「武家の用いた陣羽織(陣中で鎧・具足の上に着た上着)に形が似ていたことから」という説のほうが強いとされる。 - Wikipedia日英京都関連文書対訳コーパス
It was ranked under hitatare (samurai's large square-cut coat with cord laced sleeve edges) for seeing the shogun, daimon (daimyo's formal costume consisting of wide sleeved jacket with family crests), suo (formal middle rank dress, usually including jacket and hakama) and kamishimo (a sleeveless upper garment; formal occasion attire consisted of "upper and lower"), which is also said to be a uniform for the samurai class, and eventually was treated as casual clothing.
服装の順位としては将軍へのお目見えの時に使う直垂・大紋・素襖(すおう)、士分の制服とも言える裃より下にランクされる物で、普段着の扱いであった。 - Wikipedia日英京都関連文書対訳コーパス