• rohiṇī - sutaḥ — the son of Rohiṇī (Balarāma)
  Compound: cf. verse 1. The chapter opens and closes (almost) with this epithet for Balarāma — bracketing the violence within His maternal anchoring. Even the killer of eight is still 'mother's son'.
• parigham — club, mace
  From pari + √hṛ. The iron club — Balarāma's signature weapon (cf. plowshare too). Gauḍīyas note: Balarāma's weapons are agricultural / pastoral, not regal. He is Vraja-rasa even when destroying.
• paśūn iva — like cattle
  Compound: paśu (cattle, beast) + iva (like). The brothers are paśu before the lion. Cf. BG 16.19, where the demoniac are cast 'asurīṣu yoniṣu' — the Bhāgavatam's paśu-classification is doctrinal: demoniac jīvas are at the cattle-level of consciousness.
• mṛga - adhipaḥ — the king of beasts (lion)
  Compound: mṛga + adhipa (chief). Balarāma is lion-like in the act of killing the eight. The Bhāgavatam's typology: dharma is the lion, adharma the herd; the imbalance is built into the order of the world.

• Where do you let aftermath enemies slow you down by treating them as primary?
• How can momentum from a real victory carry through the rest?

Balarāma swings His club and kills the eight brothers as a lion kills smaller animals — paśūn iva mṛga-adhipaḥ. The Bhāgavatam frames the demoniac as paśu (cattle, lower beings) under the lion-king of dharma. The metaphor is precise: cattle are killed without anger, by structural necessity.