mas·sive / ˈmasiv/ • adj. 1. large and heavy or solid: a massive rampart of stone.2. exceptionally large: massive crowds are expected. ∎ very intense or severe: a massive heart attack. ∎ inf. particularly successful or influential: the title song became a massive hit.3. Geol. (of rocks or beds) having no discernible form or structure. ∎ (of a mineral) not visibly crystalline.DERIVATIVES: mas·sive·ly adv. a massively complicated network. mas·sive·ness n.