Business and economics

Aggregation problem (economics)
Purchasing aggregation, the joining of multiple purchasers in a group purchasing organization to increase their buying power
Community Choice Aggregation, the joining of geographically contiguous communities to bypass a conventional energy utility monopoly and seek a greener energy service

Computer science and telecommunication

Aggregate function, a type of function in data processing
Aggregation, a form of object composition in object-oriented programming
Link aggregation, using multiple Ethernet network cables/ports in parallel to increase link speed
Packet aggregation, joining multiple data packets for transmission as a single unit to increase network efficiency
Route aggregation, the process of forming a supernet in computer networking
Aggregation, a process by which Australian country television markets were combined in the late 1980s and 1990s; see Regional television in Australia

Aggregation (ethology), any gathering of organisms
Aggregation of soil granules to form soil structure
Particle aggregation, direct mutual attraction between particles (atoms or molecules) via van der Waals forces or chemical bonding
The accumulation of platelets to the site of a wound to form a platelet plug or a thrombus
Flocculation, a process where a solute comes out of solution in the form of floccules or flakes
Overdispersion or statistical aggregation, where the variance of a distribution is higher than which we expect.
Aggregation pheromone
Protein aggregation, the aggregation of mis-folded proteins