音信|おんしんonshin[0]heiban (flat)

1. nouncorrespondence; news; letter; tidings

• Synonym消息しょうそくWrittenWritten/formal prose. Refers to a person's movements or whereabouts, as in 「消息を絶つ」; centers on how someone or something is faring and where they are.
• Synonym便りたよりNeutralNews or letters from someone, as in 「便りがないのは良い便り」; can refer to the letter itself and carries a warm, personal feel.
• Synonym知らせしらせNeutralA notice or announcement of news, as in 「合格の知らせ」; stresses what is being conveyed rather than the letter itself, and can also mean an omen.
• Synonym音沙汰おとさたNeutralNews or word from someone; strongly colloquial and usually negative, as in 「音沙汰がない」. 「音信」 leans written/formal and mostly appears in 「音信不通」.

For letters and personal news, use 「便り」; for announcing news, 「知らせ」. 「音信」 is the written/formal choice for staying in touch, mostly in 「音信不通」; colloquially say 「音沙汰がない」. For someone's whereabouts, use 「消息」.

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

1. 便たより。
2. 電報でんぽうの文字数もじすうの単位たんい。最初さいしょの10文字もじが1音信おんしんで、その後あとは5文字もじで1音信おんしん。