noun, noun or participle which takes 'suru'
going off course; going out of bounds
Wasei-eigo from 'course out'. Used in sports like skiing, auto racing, and golf when a competitor leaves the designated course or track. Also used metaphorically for deviating from a planned path or procedure.
wasei-eigo (Japanese-coined English), from course out
スキーでコースアウトしてしまい、タイムが遅れた。
I went off course while skiing and my time was delayed.
話がコースアウトして、本題
The conversation went off track and we couldn't get back to the main topic.