Real Dictionary

bonsai
A bonsai or a bonsai tree is a tree or shrub that has been kept very small by growing it in a little pot and cutting it in a special way.

bonsai in American English
the art of dwarfing and shaping trees and shrubs in shallow pots by pruning, controlled fertilization, etc.
noun: a tree or shrub that has been dwarfed, as by pruning the roots and pinching, and is grown in a pot or other container and trained to produce a desired shape or effect

bonsai in British English
noun: the art of growing dwarfed ornamental varieties of trees or shrubs in small shallow pots or trays by selective pruning, etc