Refers to something that is on the edge or limit of acceptance, often of questionable quality.

संदिग्ध गुणवत्ता

English Usage: The movie was of borderline quality, not really good but not terrible either.

Hindi Usage: यह फिल्म संदिग्ध गुणवत्ता की थी, न तो वास्तव में अच्छी और न ही वास्तव में बुरी।