双|そうsou[1]atamadaka (head-high)

1. noun, noun (suffix), counterpair

• Synonym対ついNeutralThe everyday word for a pair and the usual counter, as in 「一対の花瓶」 or 「対になる」; common in speech. 「双」 mostly forms compounds like 「双方」.
• Related対ついNeutralThe everyday word for a pair and the usual counter, as in 「一対の花瓶」 or 「対になる」; common in speech. 「双」 mostly forms compounds like 「双方」.
• Related対偶たいぐうFormalFormal term for a pair, or in logic the contrapositive of a proposition; 「双」 is the shorter, simpler word.
• Antonym片かたNeutralPrefix meaning a single one or one side of what should be a pair — the opposite of paired 「双」.

For a pair or counting one, use 「対」; 「双」 also counts pairs but mostly appears in compounds like 「双方」 and 「双眼」. 「対偶」 is the formal word for a pair or the contrapositive in logic; 「片」 is the opposite, meaning just one of a pair.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 二ふたつで一いち組くみになるもの。
2. 対たいになっているものを数かぞえることば。