##### Wiktionary

**b-tree**

n. (context computing English) An indexed data structure suitable for storage of a large number of items in a balanced fashion, with very few disk hits required for locating the correct record block.

##### Wikipedia

**B-tree**

In computer science, a **B-tree** is a self-balancing tree data structure that keeps data sorted and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree is a generalization of a binary search tree in that a node can have more than two children . Unlike self-balancing binary search trees, the B-tree is optimized for systems that read and write large blocks of data. B-trees are a good example of a data structure for external memory. It is commonly used in databases and filesystems.