Archaic term for carrying two swords, typically a long sword (太刀) and a shorter companion sword (腰刀). Rare in modern Japanese; mostly encountered in historical or literary contexts.
The samurai wore two swords.
大小 is the standard term for the pair of long and short swords worn by samurai. 太刀二腰 is an archaic, less common synonym.
Compound of 太刀 (tachi, 'long sword') and 二腰 (futakoshi, 'two swords at the waist'). The exact historical derivation is uncertain; the term appears in older texts.