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。I'm sorry, but it's impossible. thank you very much (for help, etc.)
Also written 申し訳無い【もうしわけない】、申しわけない【もうしわけない】