dotty \DOT-ee\ (adjective) - 1 : Mentally unbalanced; crazy. Amusingly eccentric or unconventional. Ridiculous or absurd. 2 : Having a feeble or unsteady gait; shaky. 3 : Obsessively infatuated or enamored.
"When Roy retired from his business to play golf full-time in Florida there were those in the company who considered him dotty, while others thought him crazy like a fox."
Probably alteration of Scots dottle, silly, from Middle English doten, to dote.