How to say "concurrently" in Japanese

• 同時にどうじにCommon
  expression, adverbCovers the general sense of 'concurrently': two or more things happening at the same time. The everyday default, used freely in both speech and writing for simultaneous events, actions, or processes.
  二人ふたりの走者そうしゃは同時どうじに決勝けっしょう線せんに着ついた。↗

  The two runners reached the finish line at the same time.
• 時を同じくしてときをおなじくして
  expressionAlso means 'concurrently' or 'simultaneously', but is a less common, literary-flavored phrasing emphasizing that one event coincides with another; seldom the word you want in everyday contexts.

Both translate 'concurrently' as events happening at the same time; use the plain, common 「同時に」 for ordinary simultaneous occurrence, and the less common 「時を同じくして」 when a slightly more formal, coinciding-with tone fits.

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

• 同時にどうじにat the same time
• 時を同じくしてときをおなじくしてat the same time