The Collaborative International Dictionary of English v.0.48:

Premium \Pre"mi*um\, n.; pl. Premiums. [L. praemium,
   originally, what one has got before or better than others;
   prae before + emere to take, buy. See Redeem.]
   1. A reward or recompense; a prize to be won by being before
      another, or others, in a competition; reward or prize to
      be adjudged; a bounty; as, a premium for good behavior or
      scholarship, for discoveries, etc.
      [1913 Webster]

            To think it not the necessity, but the premium and
            privilege of life, to eat and sleep without any
            regard to glory.                      --Burke.
      [1913 Webster]

            The law that obliges parishes to support the poor
            offers a premium for the encouragement of idleness.
                                                  --Franklin.
      [1913 Webster]

   2. Something offered or given for the loan of money; bonus;
      -- sometimes synonymous with interest, but generally
      signifying a sum in addition to the capital.
      [1913 Webster]

            People were tempted to lend, by great premiums and
            large interest.                       --Swift.
      [1913 Webster]

   3. A sum of money paid to underwriters for insurance, or for
      undertaking to indemnify for losses of any kind.
      [1913 Webster]

   4. A sum in advance of, or in addition to, the nominal or par
      value of anything; as, gold was at a premium; he sold his
      stock at a premium.
      [1913 Webster]

WordNet (r) 3.0 (2006):

premium
    adj 1: having or reflecting superior quality or value; "premium
           gasoline at a premium price"
    n 1: payment for insurance [syn: premium, insurance premium]
    2: the amount that something in scarce supply is valued above
       its nominal value; "they paid a premium for access to water"
    3: a fee charged for exchanging currencies [syn: agio,
       agiotage, premium, exchange premium]
    4: a prize, bonus, or award given as an inducement to purchase
       products, enter competitions initiated by business interests,
       etc.; "they encouraged customers with a premium for loyal
       patronage"
    5: payment or reward (especially from a government) for acts
       such as catching criminals or killing predatory animals or
       enlisting in the military [syn: bounty, premium]

Moby Thesaurus II by Grady Ward, 1.0:

146 Moby Thesaurus words for "premium":
   Trinkgeld, abatement, agio, allowance, appreciation, at a premium,
   award, bait, bank discount, bank rate, bonus, bonus system, bounty,
   breakage, bribe, carrot, cash discount, chain discount, charge-off,
   come-on, compensatory interest, compound interest, concession,
   consideration, costly, cut, dear, dear-bought, decoration,
   deduction, depreciation, discount, discount rate, dividend,
   donative, double time, drawback, exceptional, exorbitant interest,
   expensive, extra, extra added attraction, extra dash, fancy, fee,
   filigree, filling, fillip, flourish, freebie, frill,
   fringe benefit, goad, gratuity, gravy, grease, gross interest,
   guerdon, high, high-priced, honorarium, importance,
   in short supply, incentive, incentive pay, incitement, inducement,
   interest, interest rate, kickback, lagniappe, largess, liberality,
   lucrative interest, lure, luxurious, meed, mortgage points,
   net interest, not affordable, of great cost, ornament,
   overtime pay, padding, palm oil, penal interest, penalty,
   penalty clause, percentage, perks, perquisite, perquisites, plum,
   pourboire, price, price of money, price reduction, price-cut,
   pricey, prize, rare, rate, rate of interest, rebate, rebatement,
   reduction, refund, regard, reward, rich, rollback, salvage, salve,
   scant, scanty, scarce, setoff, simple interest, solatium,
   something extra, sparse, sportula, spur, steep, stiff, stimulus,
   stock, store, stuffing, sumptuous, superaddition, sweetener, tare,
   time discount, tip, top, trade discount, tret, trimming, twist,
   underselling, unpayable, usury, value, wrinkle, write-off



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PREMIUM, contracts. The consideration paid by the insured to the insurer for
making an insurance. It is so called because it is paid primo, or before the
contract shall take effect. Poth. h.t. n. 81; Marah. Inst. 234.
     2. In practice, however, the premium is not always paid when the policy
is underwritten; for insurances are frequently effected by brokers, and open
accounts are kept between them and the underwriters, in which they make
themselves debtors for all premiums;, and sometimes notes or bills are given
for the amount of the premium.
     3. The French writers, when they speak of the consideration given for
maritime loans, employ a variety of words in order to distinguish it
according to the nature of the case. Thus, they call it interest when it is
stipulated to be paid by the month or at other stated periods. It is a
premium, when a gross sum is to be paid at the end of a voyage, and here the
risk is the principal object which they have in view. When the sum is a
percentage on the money lent, they denominate it exchange, considering it in
the light of money lent in one place to be returned in another, with a
difference in amount between the sum borrowed and that which is paid,
arising from the difference of time and place. When they intend to combine
these various shades into one general denomination, they make use of the
term maritime profit, to convey their meaning. Hall on Mar. Loans, 56, n.
Vide Park, Ills. h.t. Poth. h.t.; 3 Kent, Com. 285; 15 East, R. 309, Day's
note, and the cases there cited.