The price at which a share can be traded. This is not any single amount: even for widely traded shares the offer price at which market-makers are willing to sell shares is higher than the bid price at which they are willing to buy. The average of these, the mid-market price, is frequently quoted in the financial press. In the case of shares which are little traded, the reported price may simply be the last one at which any transactions were reported, and may give little guidance on the terms on which they can now be traded.
Reference: Oxford Press Dictonary of Economics, 5th edt.