noun

• (geology, volcanology) A mass of angular volcanic fragments united by heat; distinguished from conglomerate.
• (meteorology) An ice cover of floe formed by the freezing together of various forms of ice.

verb

• (ambitransitive) To wind or collect into a ball; hence, to gather into a mass or anything like a mass.
  "The bustle of a croud is not ill-adapted to the pencil: but the management of it requires great artifice. The whole must be massed together, and considered as one body. ¶ I mean not to have the whole body so agglomerated, as to consist of no detached groups: but to have these groups […] appear to belong to one whole, by the artifice of composition, and the effect of light."
• (geography) To extend an urban area by contiguous development, so as to merge the built-up area of one or more central cities or settlements and their suburbs (thus creating an agglomeration).