noun which may take the genitive case particle 'no'
in progress; during execution; runtime
Used as a no-adjective to describe something that is currently being carried out, especially in computing or formal contexts.
プログラムは現在実行中です。
The program is currently running.
実行中のタスクを確認してください。
Please check the tasks in progress.
Compound of 実行 (jikkō, 'execution') + 中 (chū, 'in the middle of').