同時

1. Origins, structure, and basic meaning

• Structure: 同時 is read as どうじ and is a noun-like expression for two or more events or states occurring at the same time.
• Basic usage: Two people answering simultaneously appear in 二人が同時に答える, while carrying out tasks together in time appears in 同時に進める.

2. Common pitfalls and similar expressions

• The adverbial form 同時に
  • Adding に lets the expression modify a verb and state that actions occur at the same time.
• Difference from 一緒に
  • Unlike the word for people or actions being together, this expression focuses on the temporal relation of events occurring at the same moment.