means A light frame covered in fabric or paper that flies on the end of a string when the wind catches it — and, by extension, a check written against funds that aren't there yet.

from From Old English 'cyta,' the name of a graceful, hovering bird of prey — the kite that hangs almost motionless in the wind. When people built a flying toy that did the same, they borrowed the bird's name for it. The financial sense ('to kite a check') is a much later cousin, picturing money that floats and dangles in the air much as the toy does — value held aloft by nothing but optimism and string.