The same time; two or more events occurring at the same time (often used as 'simultaneously' in speech).
試験は全国で同時に行われる。
The exam is held simultaneously nationwide.
彼らは同時に部屋に入ってきた。
They entered the room at the same time.
会議と授業が同時で、どちらに行くか迷った。
The meeting and the class were at the same time, so I was unsure which to attend.
Describing events that occur concurrently or synchronously; used to indicate things happening at the same time (can be used prenominally or adverbially).
複数のタスクを同時に処理するのは難しい。
It's difficult to process multiple tasks at the same time.
同時開催のイベントが二つある。
There are two events being held concurrently.
同時進行でプロジェクトを進める必要がある。
We need to advance the projects in parallel/simultaneously.