Polus is a common adjective/adverb meaning many (plural) or much (singular), occurring about 365 times in the NT. As a substantive it means "many people" or "a large quantity." As an adverb (neuter polu) it means "greatly," "much," or "by far."
It forms the basis of several important compound words: polupoikilos (manifold, Ephesians 3:10), polusplagchnos (very compassionate, James 5:11), and polumerōs (in many portions, Hebrews 1:1). The prefix poly- amplifies.
The key theological phrase is hoi polloi — "the many." In Mark 10:45 and Romans 5:15–19, "the many" describes those impacted by Adam's sin and by Christ's righteousness. Some interpret this as "all" (universal), others as "the multitude who believe" (corporate). Either way, Christ's work is vast in scope.
"Much more" (pollō mallon) is Paul's rhetorical escalation in Romans 5:9–10, 15, 17: if the lesser gift was given (Christ died for sinners), "how much more shall we be saved through his life!" The logic of grace is always surplus, overflow, abundance.
The multiplication of the loaves — five loaves feeding many thousands with baskets left over — is a sign pointing to Christ's inexhaustible provision. Polus in miracle contexts signals the extravagance of divine supply.