connective N2 common politewritten
と同時に — at the same time as
と同時に ・ とどうじに
Meaning
① simultaneous: at the same time as ~ / the moment ~ — two events happen in the same instant
② two aspects: and at the same time / while also being ~ — one thing is two things at once
Key sentence
① simultaneous
ベルが鳴ると同時に、生徒たちは教室を出た。
The moment the bell rang, the students left the classroom.
② two aspects
彼は医者であると同時に、作家でもある。
He is a doctor and at the same time a novelist.
Formation
| Attaches to | Form | Example |
|---|---|---|
| Verb (dictionary) / Nである / plain clause + と同時に | [Vる / Nである] + と同時に | 卒業すると同時に / リーダーであると同時に |
Examples
① simultaneous
ドアを開けると同時に、猫が飛び出した。
The instant I opened the door, the cat shot out.
② two aspects
これは挑戦であると同時に、大きな責任でもある。
This is a challenge and, at the same time, a great responsibility.
Easily confused with
とともに と同時に pins two things to the *same instant* or asserts two simultaneous facets; とともに covers accompaniment and *gradual* parallel change over time. 'The moment the bell rang' = と同時に; 'as the years passed' = とともに. ながら ながら = one person doing two actions concurrently (歩きながら, 'while walking'); と同時に marks two *events* coinciding in time, with possibly different subjects (the bell rang と同時に the students left).
Notes
- 同時 = 'the same time'. The 'two aspects' sense (X であると同時に Y) is common in formal description, presenting one entity as simultaneously two things.
See と同時に in real sentences
Jengo shows と同時に the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Advanced Japanese Grammar, A Dictionary of Intermediate Japanese Grammar.