1. Expressions (phrases, clauses, etc.), I-adjective (keiyoushi)

   I'm sorry; (it's) inexcusable; I feel regretful; I feel guilty

   申し訳ないけど、できません。

2. thank you very much (for help, etc.)

Also written 申し訳無い【もうしわけない】moushiwakenai、申しわけない【もうしわけない】moushiwakenai