Sharma / Santhanam / Tara Chandra (śl. 14) / Girdhari Lal / Ganesha Datta Pathaka (śl. 13):
संकर्षणश्च प्रद्युम्नोऽनिरुद्ध इति मूर्तिधृक् । तमःशक्त्याऽन्वितो विष्णुर्देवः संकर्षणाभिधः ॥ १५ ॥
saṃkarṣaṇaśca pradyumno’niruddha iti mūrtidhṛk |
tamaḥśaktyā’nvito viṣṇurdevaḥ saṃkarṣaṇābhidhaḥ || 15 ||
Translation: Sankarṣaṇa, Pradyumna and Aniruddha (saṃkarṣaṇaś-ca pradyumno ’niruddha) are forms that He is bearing (iti mūrti-dhṛk). When He is conjoined with Tamas-śakti (tamaḥ-śaktyā ’nvito), then God Viṣṇu’s name is Sankarṣaṇa (viṣṇur-devaḥ saṃkarṣaṇa-ābhidhaḥ).
dhṛk N.sg. from dhṛt - holding, bearing, supporting, wearing, having, possessing.