What does agglomerate mean?
An agglomerate is a shapeless mass of things that have collected together without any organizing principle — a jumbled cluster rather than a designed assembly. The word is most familiar in two technical settings. In geology, an agglomerate is a coarse volcanic rock made of angular blocks of lava and other ejecta bound in a finer ash matrix; its angular fragments distinguish it from a conglomerate, whose pebbles are rounded by water. More broadly, the term describes anything heaped or clustered indiscriminately, and it appears frequently in economics and urban studies through its derivative 'agglomeration', used for cities and industries that grow by accretion around a core. As a verb, 'to agglomerate' means to gather into such a mass. Derived from the Latin glomerare, 'to wind into a ball', the word shares its root with 'conglomerate' and 'glomeration'. It is a precise, somewhat formal word, valued where writers want to emphasize disorderly accumulation rather than purposeful combination.
A mass or cluster of things gathered together without order; specifically in geology, a volcanic rock composed of angular fragments of lava or tuff cemented in a finer matrix.
"The outcrop consisted of a coarse agglomerate of angular lava blocks embedded in compacted ash."
In geology, the angular nature of the fragments distinguishes agglomerate from conglomerate.
To gather or cause to gather into a mass, cluster, or heap.
"Dust and debris slowly agglomerated in the corner of the abandoned warehouse."
Stress falls on the second syllable in the verb form, unlike the noun.
Formed or gathered into a clustered, ball-like mass.
"The pollen grains appeared under the microscope as small agglomerate clusters."
Less common than the noun and verb forms; often written 'agglomerated'.
The plural is standard when referring to multiple rock specimens or multiple distinct masses; in geological literature, individual occurrences are usually described with the singular.
"The survey catalogued several distinct agglomerates along the caldera's northern rim."
Geologists can tell whether a rock formed from a violent volcanic eruption or a gentle riverbed just by checking whether its pebbles are angular (agglomerate) or rounded (conglomerate).
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of agglomerate
Agglomerate comes from the Latin verb glomerare, meaning 'to wind up into a ball', prefixed with ad- ('toward'), giving agglomerare, 'to gather into a ball or mass'. It entered English in the late seventeenth century, initially in scientific writing describing clustered masses. Its closest relative is 'conglomerate', built on the same Latin root but with com- ('with') instead of ad-, and both words were adopted by nineteenth-century geologists to name distinct rock types distinguished by fragment shape.
Related word forms
How agglomerate is actually used
The word carries a slightly technical, formal register: it is most at home in geology, volcanology, and discussions of urban clustering (usually via its derivative 'agglomeration'). Unlike 'aggregate', which implies a deliberate mixture, 'agglomerate' implies an accidental or unstructured clumping. The noun is stressed on the first syllable, while the verb is stressed on the second — a stress shift worth noting when speaking aloud.
Easily confused with agglomerate
A conglomerate is a sedimentary rock made of rounded pebbles cemented together, whereas an agglomerate is a volcanic rock of angular fragments; as general nouns, conglomerate also suggests a large business corporation.