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.
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   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.
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            People were tempted to lend, by great premiums and
            large interest.                       --Swift.
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   3. A sum of money paid to underwriters for insurance, or for
      undertaking to indemnify for losses of any kind.
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   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]