agglomeration

noun

Etymology: From Latin agglomerātiō. By surface analysis, agglomerate + -ion.

1. The act or process of collecting in a mass; a heaping together.
2. State of being collected in a mass; a mass; cluster.
3. An extended city area comprising the built-up area of a central city and any suburbs linked by continuous urban area.
4. A mass of large volcanic fragments bonded under heat.