buyback

1. An act of buying something that one previously sold or owned.
2. The repurchase of stock by the company that issued it, as to reduce holdings of a single investor or increase the value of shares by reducing their number.

The buying back of outstanding shares (repurchase) by a company in order to reduce the number of shares on the market. Companies will buyback shares either to increase the value of shares still available (reducing supply), or to eliminate any threats by shareholders who may be looking for a controlling stake.

Investopedia Says:
A buyback is a method for company to invest in itself since they can't own themselves. Thus, buybacks reduce the number of shares outstanding on the market which increases the proportion of shares the company owns. Buybacks can be carried out in two ways:

1. Shareholders may be presented with a tender offer whereby they have the option to submit (or tender) a portion or all of their shares within a certain time frame and at a premium to the current market price. This premium compensates investors for tendering their shares rather than holding on to them.

2. Companies buy back shares on the open market over an extended period of time.

Related Links:
Find out what these company programs achieve and what it means for stockholders. A Breakdown Of Stock Buybacks
Perhaps the real cost of employee stock options is already accounted for in the expense of buyback programs. The "True" Cost of Stock Options

1. In a foreign debt restructuring, an agreement by a debtor nation to buy outstanding loans from creditor banks at fair market value. Funds to purchase unpaid loans, normally at a deep discount from face value or book value, come from a variety of sources: export earnings, tourism, and direct loans or grants from the International Monetary Fund and other international credit agencies.

2. Offer by a corporation to repurchase its own stock from shareholders, done to raise the price of its stock or fend off a hostile takeover.

3. Repurchase Agreement.

The noun has one meaning:

Meaning #1: purchasing back something previously sold
  Synonyms: redemption, repurchase