The Collaborative International Dictionary of English v.0.48:

Exponent \Ex*po"nent\, n. [L. exponens, -entis, p. pr. of
   exponere to put out, set forth, expose. See Expound.]
   1. (Alg.) A number, letter, or any quantity written on the
      right hand of and above another quantity, and denoting how
      many times the latter is repeated as a factor to produce
      the power indicated;

   Note: thus a^2 denotes the second power, and a^x the xth
         power, of a (2 and x being the exponents). A fractional
         exponent, or index, is used to denote the root of a
         quantity. Thus, a^1/3 denotes the third or cube root
         of a.
         [1913 Webster]

   2. One who, or that which, stands as an index or
      representative; as, the leader of a party is the exponent
      of its principles.
      [1913 Webster]

   3. one who explains, expounds, or interprets.
      [PJC]

   Exponent of a ratio, the quotient arising when the
      antecedent is divided by the consequent; thus, 6 is the
      exponent of the ratio of 30 to 5. [R.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

exponent
    n 1: a person who pleads for a cause or propounds an idea [syn:
         advocate, advocator, proponent, exponent]
    2: someone who expounds and interprets or explains
    3: a mathematical notation indicating the number of times a
       quantity is multiplied by itself [syn: exponent, power,
       index]

Moby Thesaurus II by Grady Ward, 1.0:

128 Moby Thesaurus words for "exponent":
   Maecenas, abettor, admirer, advocate, aficionado, allegorist,
   alter ego, alternate, amicus curiae, angel, annotator, apologist,
   attorney, backer, backup, backup man, booster, buff, case,
   case in point, champion, cicerone, clarifier, commentator, critic,
   cross section, cryptanalyst, cryptographer, cryptologist, decoder,
   defender, definer, demonstration, demonstrator, demythologizer,
   dependence, deputy, diaskeuast, dragoman, dummy, editor, emblem,
   embodiment, emendator, emender, encourager, endorser, euhemerist,
   example, executive officer, exegesist, exegete, exegetist,
   exemplar, exemplification, explainer, explanation, explicator,
   expositor, expounder, fan, favorer, figurehead, friend at court,
   go-between, guide, hermeneut, illustration, instance, interpreter,
   lexicographer, lieutenant, locum, locum tenens, lover, mainstay,
   maintainer, metaphrast, object lesson, oneirocritic, paranymph,
   paraphrast, partisan, patron, pinch hitter, pleader, procurator,
   promoter, proponent, protagonist, proxy, relevant instance,
   reliance, representation, representative, scholiast, second,
   second in command, secondary, seconder, sectary, sider, specimen,
   sponsor, stalwart, stand-in, standby, substitute, support,
   supporter, surrogate, sustainer, symbol, sympathizer,
   textual critic, translator, type, typical example, typification,
   understudy, upholder, utility man, vicar, vicar general, vice,
   vicegerent, votary, well-wisher



The Free On-line Dictionary of Computing (30 December 2018):

exponent

    (Or "characteristic") The part of a
   floating-point number specifying the power of ten by which
   the mantissa should be multiplied.  In the common notation,
   e.g. 3.1E8, the exponent is 8.

   (1995-02-27)