Full Buy
A full buy is a buy-in of at least the minimum amount of chips required for a particular game.
The simple explanation
Many games have a minimum buy-in. If you buy in for at least that amount, you have made a full buy.
A closer look
Some rooms allow a short buy for less than the minimum in certain conditions, but a full buy is the standard. A larger stack gives you more options after the flop, so many players buy in for the maximum or close to it. Know the minimum and the maximum of the game before you sit.
A practical example
A game requires a $100 minimum buy-in. A player buys in for $100 and makes a full buy.
Full explanation
A full buy is a buy-in of at least the minimum amount of chips required for a particular game.
A full buy meets the minimum buy-in.
Short buys may be allowed in some rooms.
A bigger stack gives more options.
Know the minimum and maximum.