封筒|ふうとうfuutou[0]heiban (flat)

1. nounenvelope
   だれがこの封筒ふうとうを破やぶって開あけたのか。↗

   Who has torn the envelope open?

• SynonymエンベロープNeutralLoanword for an envelope, uncommon in everyday speech; mostly seen in technical or design fields.
• Related状袋じょうぶくろWrittenOld-fashioned term for an envelope; in modern Japanese 「封筒」 is the usual word.
• Related状ぶくろWrittenKana spelling of 「状袋」; an old-fashioned word for an envelope, now rarely used. Written/formal prose.

For an envelope, 「封筒」 is the default choice. 「状袋」 and 「状ぶくろ」 are old-fashioned written terms rarely used today; 「エンベロープ」 is a loanword mostly confined to technical or design fields.

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

1. 手紙てがみ・書類しょるいなどを封入ふうにゅうする方形ほうけいの紙袋かみぶくろ。