WordNet (r) 3.0 (2006):

gene
    n 1: (genetics) a segment of DNA that is involved in producing a
         polypeptide chain; it can include regions preceding and
         following the coding DNA as well as introns between the
         exons; it is considered a unit of heredity; "genes were
         formerly called factors" [syn: gene, cistron, factor]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "gene":
   Altmann theory, DNA, DNA double helix, De Vries theory,
   Galtonian theory, Mendelianism, Mendelism, RNA, Verworn theory,
   Weismann theory, Weismannism, Wiesner theory, allele, allelomorph,
   anticodon, biotype, birth, character, chromatid, chromatin,
   chromosome, codon, deoxyribonucleic acid, determinant, determiner,
   diathesis, endowment, eugenics, factor, gene complex, gene flow,
   gene pool, genesiology, genetic code, genetic drift, genetics,
   genotype, hereditability, hereditary character, heredity,
   heritability, heritage, inborn capacity, inheritability,
   inheritance, mRNA, matrocliny, messenger RNA, nucleotide,
   operator gene, operon, patrocliny, pharmacogenetics,
   recessive character, regulator gene, replication, ribosomal RNA,
   structural gene, tRNA, transfer RNA