unison

• n.ハーモニー; ユニゾンの歌唱; ホモフォニー; [音]同音
• n.(ユニゾン)人名;(英)ユニゾン

un-、1つ、語源的にはunitと同じ、-son、音、語源的にはsoundと同じ、つまり同じ音、ひいてはユニゾン、ハーモニー。

unison

unison: [16] Unison originated as a musical term, denoting ‘of the same sound’. It comes via Old French unison from late Latin ūnisonus, a compound adjective formed from ūnus ‘one’ and sonus ‘sound’ (source of English sound). The metaphorical sense ‘agreement, concord’ emerged in the 17th century.
=> sound

unison (n.)

1570s, "note having the same pitch as another; identity in pitch of two or more sounds; interval between tones of the same pitch," especially the interval of an octave, from Middle French unisson "unison, accord of sound" (16c.) or directly from Medieval Latin unisonus "having one sound, sounding the same," from Late Latin unisonius "in immediate sequence in the scale, monotonous," from Latin uni- "one" (see one) + sonus "sound" (see sound (n.1)). Figurative sense of "harmonious agreement" is first attested 1640s.

1. 72,000 pairs of hands clapped in unison to the song.

72000両手と歌が整然と拍子をとっている。

2.The international community is ready to work in unison against him.

国際社会は手を組んで彼に反対する準備をしている。

3.The governments acted in unison to combat terrorism.

これらの国の政府はテロ対策に一致して行動している。

4.They ran together，their legs moving in unison .

彼らは足並みをそろえて一緒に走った。

5. Unison and the other unions have the power to hold the Government to ransom.

公務員労働組合やその他の労働組合は政府を脅迫する能力がある。