The Collaborative International Dictionary of English v.0.48:

Outgrowth \Out"growth`\, n.
   That which grows out of, or proceeds from, anything; an
   excrescence; an offshoot; hence, a result or consequence.
   [1913 Webster]

WordNet (r) 3.0 (2006):

outgrowth
    n 1: a natural consequence of development [syn: outgrowth,
         branch, offshoot, offset]
    2: the gradual beginning or coming forth; "figurines presage the
       emergence of sculpture in Greece" [syn: emergence,
       outgrowth, growth]
    3: a natural prolongation or projection from a part of an
       organism either animal or plant; "a bony process" [syn:
       process, outgrowth, appendage]

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "outgrowth":
   artifact, benign tumor, brainchild, budding, burgeoning,
   by-product, callosity, callus, cancer, carcinoma, child, coinage,
   composition, concoction, consequence, consequent, corn, corollary,
   creation, creature, crowning achievement, cyst, derivation,
   derivative, development, distillate, distillation, effect,
   end product, essence, event, eventuality, eventuation, excrescence,
   extract, fruit, fungosity, fungus, gemmation, germination, growth,
   handiwork, harvest, intumescence, invention, issue, legacy,
   logical outcome, malignant growth, manufacture, masterpiece,
   masterwork, maturation, metastatic tumor, mintage, mole,
   morbid growth, neoplasm, nevus, new mintage, nonmalignant tumor,
   offshoot, offspring, opera, opus, opuscule, origination, outcome,
   overgrowth, precipitate, procreation, product, production,
   proud flesh, pullulation, reproduction, result, resultant, sarcoma,
   sequel, sequela, sequence, sequent, side issue, sprouting, tumor,
   upgrowth, upshot, vegetation, verruca, wart, wen, work