The Collaborative International Dictionary of English v.0.48:

Offspring \Off"spring`\, n. sing. & pl. [Off + spring.]
   [1913 Webster]
   1. The act of production; generation. [Obs.]
      [1913 Webster]

   2. That which is produced; a child or children; a descendant
      or descendants, however remote from the stock.
      [1913 Webster]

            To the gods alone
            Our future offspring and our wives are known.
                                                  --Dryden.
      [1913 Webster]

   3. Origin; lineage; family. [Obs.] --Fairfax.
      [1913 Webster]

WordNet (r) 3.0 (2006):

offspring
    n 1: the immediate descendants of a person; "she was the mother
         of many offspring"; "he died without issue" [syn:
         offspring, progeny, issue]
    2: something that comes into existence as a result;
       "industrialism prepared the way for acceptance of the French
       Revolution's various socialistic offspring"; "this skyscraper
       is the solid materialization of his efforts" [syn:
       offspring, materialization, materialisation]
    3: any immature animal [syn: young, offspring]

Moby Thesaurus II by Grady Ward, 1.0:

137 Moby Thesaurus words for "offspring":
   aftermath, artifact, bairn, brainchild, breed, brood, by-product,
   cherub, child, children, chit, coinage, composition, conclusion,
   concoction, consequence, consequent, corollary, creation, creature,
   crowning achievement, darling, daughter, derivation, derivative,
   descendant, descendants, descent, development, distillate,
   distillation, dynasty, effect, end product, essence, event,
   eventuality, eventuation, extract, family, folks, foster child,
   fruit, get, grandchild, grandchildren, granddaughter, grandson,
   great-grandchildren, handiwork, harvest, hatch, hearth, heir,
   heiress, heirs, homefolks, hostages to fortune, house, household,
   inheritors, innocent, invention, issue, kid, kids, kitten, lamb,
   lambkin, legacy, line, lineage, little bugger, little fellow,
   little guy, little innocent, little one, little ones, little tad,
   little tot, logical outcome, manufacture, masterpiece, masterwork,
   menage, mintage, mite, new generation, new mintage, nipper,
   offshoot, opera, opus, opuscule, origination, outcome, outgrowth,
   peewee, people, posterity, precipitate, produce, product,
   production, progeniture, progeny, result, resultant,
   rising generation, scion, seed, sequel, sequela, sequence, sequent,
   shaver, son, son and heir, sonny, sons, spawn, stepchild,
   stepdaughter, stepson, succession, successor, swarm, tad, tot,
   treasures, upshot, wee tot, work, young, younglings, youngster,
   youngsters