flocculate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To cause (individual particles of clay) to aggregate into clotlike masses or precipitate into small lumps.
• intransitive verb To cause (clouds) to form fluffy masses.
• intransitive verb To form lumpy or fluffy masses.

from The Century Dictionary.

• To form visible loosed light masses, or flocculi, as of clay in soil-water or of nitrogenous substances in milk. The addition of lime or salt causes soil-water to flocculate; ammonia prevents the flocculation or breaks it up. A sheet of uniform stratus cloud often flocculates with numerous cirro-cumulus or alto-cumulus clouds arranged in rank and file.
• In entomology, bearing a flocculus or small bunch of curled hairs, as the trochanters of certain bees.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb (Geol.) To aggregate into small lumps.
• adjective (Zoöl.) Furnished with tufts of curly hairs, as some insects.
• transitive verb To convert into floccules or flocculent aggregates; to make granular or crumbly.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To collect together in a loose aggregation like flocks (tufts) of wool.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb form into an aggregated lumpy or fluffy mass
• verb cause to become a fluffy or lumpy aggregate