The Collaborative International Dictionary of English v.0.48:

Cyclic \Cyc"lic\ (s?k"l?k or s?"kl?k), Cyclical \Cyc"lic*al\
   (s?k"l?-kal), a. [Cf. F. cycluque, Gr. kykliko`s, fr. ky`klos
   See Cycle.]
   1. Of or pertaining to a cycle or circle; moving in cycles;
      as, cyclical time. --Coleridge.
      [1913 Webster]

   2. (Chemistry) Having atoms bonded to form a ring structure.
      Opposite of acyclic.

   Note: Used most commonly in respect to organic compounds.

   Note: [Narrower terms: bicyclic; heterocyclic;
         homocyclic, isocyclic]

   Syn: closed-chain, closed-ring.
        [WordNet 1.5]

   3. Recurring in cycles[2]; having a pattern that repeats at
      approximately equal intervals; periodic. Opposite of
      noncyclic.

   Note: [Narrower terms: alternate(prenominal),
         alternating(prenominal); alternate(prenominal), every
         other(prenominal), every second(prenominal);
         alternating(prenominal), oscillating(prenominal);
         biyearly; circadian exhibiting 24-hour
         periodicity); circular; daily, diurnal;
         fortnightly, biweekly; hourly; midweek,
         midweekly; seasonal; semestral, semestrial;
         semiannual, biannual, biyearly; semiweekly,
         biweekly; weekly; annual, yearly; biennial;
         bimonthly, bimestrial; half-hourly; half-yearly;
         monthly; tertian, alternate(prenominal);
         triennial]
         [WordNet 1.5]

   4. Marked by repeated cycles[2].
      [WordNet 1.5]

   Cyclic chorus, the chorus which performed the songs and
      dances of the dithyrambic odes at Athens, dancing round
      the altar of Bacchus in a circle.

   Cyclic poets, certain epic poets who followed Homer, and
      wrote merely on the Trojan war and its heroes; -- so
      called because keeping within the circle of a single
      subject. Also, any series or coterie of poets writing on
      one subject. --Milman.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Biennial \Bi*en"ni*al\, a. [L. biennalis and biennis, fr.
   biennium a space of two years; bis twice + annus year. Cf.
   Annual.]
   1. Happening, or taking place, once in two years; as, a
      biennial election.
      [1913 Webster]

   2. (Bot.) Continuing for two years, and then perishing, as
      plants which form roots and leaves the first year, and
      produce fruit the second.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Biennial \Bi*en"ni*al\, n.
   1. Something which takes place or appears once in two years;
      esp. a biennial examination.
      [1913 Webster]

   2. (Bot.) A plant which exists or lasts for two years.
      [1913 Webster]

WordNet (r) 3.0 (2006):

biennial
    adj 1: having a life cycle lasting two seasons; "a biennial life
           cycle"; "parsnips and carrots are biennial plants often
           grown as annuals" [syn: biennial, two-year] [ant:
           annual, one-year, perennial]
    2: occurring every second year; "they met at biennial
       conventions" [syn: biennial, biyearly]
    n 1: (botany) a plant having a life cycle that normally takes
         two seasons from germination to death to complete;
         flowering biennials usually bloom and fruit in the second
         season

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "biennial":
   amphibian, angiosperm, anniversary, annual, annual holiday,
   aquatic plant, biannual, bicentenary, bicentennial, bimonthly,
   birthday, bissextile day, biweekly, catamenial, centenary,
   centennial, commemoration, cosmopolite, cutting, daily, decennial,
   deciduous plant, diamond jubilee, dicot, dicotyledon, diurnal,
   ephemeral, evergreen, exotic, flowering plant, fortnightly, fungus,
   gametophyte, golden wedding anniversary, gymnosperm, hebdomadal,
   holy days, hourly, hydrophyte, immovable feast, jubilee, leap year,
   menstrual, momentary, momently, monocot, monocotyl, monthly,
   name day, natal day, octennial, perennial, plant, polycot,
   polycotyl, polycotyledon, quadrennial, quarterly,
   quasquicentennial, quincentenary, quincentennial, quinquennial,
   quotidian, secular, seed plant, seedling, semestral, semiannual,
   semimonthly, semiweekly, semiyearly, septennial, sesquicentennial,
   sextennial, silver wedding anniversary, spermatophyte, sporophyte,
   tercentenary, tercentennial, tertian, thallophyte, tricennial,
   triennial, vascular plant, vegetable, wedding anniversary, weed,
   weekly, yearly