長らく (nagaraku) Japanese meaning: for a long time | KotomoraI'm sorry to have kept you waiting for so long.
He lived abroad for a long time.
Usage patterns
長らくお待たせいたしましたsorry to have kept you waiting so long (formal)
Sorry to have kept you waiting so long. I'll show you in now.
長らくご無沙汰しておりますapologizing for not having been in touch for a long time (formal)
I'm sorry it's been so long since I last wrote; I hope you're well.
長らく〈動詞〉ておりましたhave been doing something for a long time (formal, polite)
This system had been in use for a long time.
長らくのご愛顧long-standing patronage or support (formal, business context)
We thank you for your long-standing patronage.