• mahā-tālaḥ — the great palm tree
  mahā (great) + tāla (palm). The tallest palm in Tālavana. Gauḍīya: the size of the tree marks the size of the kill; Balarāma's throw clears the tallest of the grove.
• vepamānaḥ — trembling
  Present middle participle of √vip — to tremble. Gauḍīya: trees trembled because Bhagavān's strength contacted them; the same trees that bowed in verse 4 with fruit now bow again, this time with cascading impact.
• pārśva-stham — another situated beside it
  pārśva (side) + stha (standing). The neighbor-tree. Gauḍīya note: pārśva-stham implies the trees of Tālavana stand in close-packed rows — their density is part of why this is a forest at all. The kill takes advantage of the density.
• bhagnaḥ — broken
  Past participle of √bhañj — to break. Gauḍīya: the same root as bhaṅga (rupture). The tree's bhaṅga is also Dhenuka's bhaṅga — both broken in one impact. Their fates merge mid-air.
• bṛhat-śirāḥ — which had a large top
  bṛhat (large) + śiras (head, top). Gauḍīya: bṛhat is the same root as bṛhaspati and brahman — that which is great. Even the tree's top is named with a sacred adjective. Vraja's vocabulary sanctifies even the kill-impact zone.

• Which 'master obstacle' of mine, if it fell, would topple many smaller ones?
• Am I picking at the small trees when the chain begins with one big throw?

A row of palms standing close enough that one falling fells the next, then the next, then the next — a cascade. Dhenuka's body hits the tallest palm; the palm sways, hits its neighbor, the neighbor hits its neighbor, the entire grove rocks. The verse extends the kill into landscape-scale consequence. One asura's death is heard by a forest.