The Collaborative International Dictionary of English v.0.48:

Elemental \El`e*men"tal\ ([e^]l`[-e]*m[e^]n"tal), a.
   1. Pertaining to the elements, first principles, and primary
      ingredients, or to the four supposed elements of the
      material world; as, elemental air. "Elemental strife."
      --Pope.
      [1913 Webster]

   2. Pertaining to rudiments or first principles; rudimentary;
      elementary. "The elemental rules of erudition."
      --Cawthorn.
      [1913 Webster]

WordNet (r) 3.0 (2006):

elemental
    adj 1: relating to or being an element; "elemental sulphur"
    2: relating to severe atmospheric conditions; "a race against
       hail or cold rains or some other elemental catastrophe"-
       J.K.Howard
    3: of or being the essential or basic part; "an elementary need
       for love and nurturing" [syn: elementary, elemental,
       primary]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "elemental":
   ab ovo, abecedarian, aboriginal, acid, aerographic, aerologic,
   alkali, antenatal, autochthonous, baric, barographic, barometric,
   basal, basic, basilar, beginning, biochemical, budding, central,
   chemical, chemicobiological, chemicoengineering,
   chemicomineralogical, chemicophysical, chemurgic, climatologic,
   connate, constituent, constitutional, constitutive, copolymeric,
   copolymerous, creative, crucial, cyclonic, deep-seated, dimeric,
   dimerous, electrochemical, elemental spirit, elementary, embryonic,
   essential, fetal, formative, foundational, fundamental, generative,
   genetic, germinal, gestatory, gnome, gut, heteromerous,
   high-pressure, in embryo, in its infancy, in ovo, in the bud,
   inaugural, inborn, inceptive, inchoate, inchoative, incipient,
   incunabular, infant, infantile, ingrained, inherent, initial,
   initiative, initiatory, innate, intimate, intrinsic, introductory,
   inventive, isobaric, isomerous, isometric, isopiestic,
   macrochemical, macroclimatic, material, metameric, meteorologic,
   microclimatic, microclimatologic, monomerous, nascent, natal,
   nonacid, of the essence, original, parturient, photochemical,
   physicochemical, phytochemical, polymeric, postnatal, pregnant,
   prenatal, primal, primary, prime, primeval, primitive, primogenial,
   primordial, pristine, procreative, protogenic, radical,
   radiochemical, rudimental, rudimentary, salamander, seminal,
   substantial, substantive, sylph, thermochemical, underlying,
   undine, ur