A conjunction used after the attributive form of a verb or adjective to state a reason or circumstance; often carries an apologetic or explanatory nuance. Colloquial variant: もんだから.
急に熱が出たものだから、今日は会社を休みました。
Because I suddenly had a fever, I took the day off from work.
遅れてすみません、電車が遅延したものだから間に合わなかったんです。
Sorry I'm late — the train was delayed, so I couldn't make it on time.
子どもが泣き止まないもんだから、話を続けられなかった。
My child wouldn't stop crying, so I couldn't continue the conversation.
雨で道がぬかるんでいるものだから、今日は散歩に行けない。
Since the roads are muddy from the rain, I can't go for a walk today.