That intellect, O Arjuna, which is enveloped in darkness and sees Adharma as Dharma and all things perverted, is Tamasic (dark).

Swami Sivananda

O Partha, that intellect is born of tamas which, being covered by darkness, considers vice as virtue, and indeed perceives all things contrary to what they are.

Swami Gambirananda

Follows the commentary of Shankara (Advaita).

That Buddhi, O Arjuna, which, enveloped in darkness, regards Adharma as Dharma and reverses every value, is Tamasika.

Swami Adidevananda

Follows the commentary of Ramanuja (Vishishtadvaita).

The intellect which, containing darkness (ignorance), conceives the unrighteous one as righteous and all things topsy-turvy—that intellect is deemed to be of the Tamas (Strand).

Dr. S. Sankaranarayan

Follows the commentary of Abhinavagupta (Kashmir Shaivism).

And that which, shrouded in Ignorance, thinks wrong to be right, and sees everything perversely, O Arjuna, that intellect is ruled by Darkness.

Shri Purohit Swami

हे पृथानन्दन ! तमोगुणसे घिरी हुई जो बुद्धि अधर्मको धर्म और सम्पूर्ण चीजोंको उलटा मान लेती है, वह तामसी है।

Swami Ramsukhdas

हे पार्थ ! तमस् (अज्ञान अन्ध:कार) से आवृत जो बुद्धि अधर्म को ही धर्म मानती है और सभी पदार्थों को विपरीत रूप से जानती है, वह बुद्धि तामसी है।

Swami Tejomayananda