set of three (hanging scrolls)
Specifically refers to a set of three hanging scrolls (kakejiku) displayed together, often as a triptych. The cross-reference 三幅対 is a synonymous term.
See also: 三幅対
A set of three hanging scrolls is displayed in the alcove.
Synonymous; 三幅一対 uses 一対 (one pair) to emphasize the set, while 三幅対 is a more compact form.
Compound of 三幅 (three widths/scrolls) and 一対 (one pair/set). The exact historical derivation is uncertain, but the term is used in the context of traditional Japanese hanging scroll display.