JEOFAIL
JEOFAILS
JEON
JEOPARD
JEOPARDED
JEOPARDER
JEOPARDERS
JEOPARDIED
JEOPARDIES
JEOPARDING
JEOPARDISE
JEOPARDISED
JEOPARDISES
JEOPARDISING
JEOPARDIZE
JEOPARDIZED
JEOPARDIZES
JEOPARDIZING
JEOPARDOUS
JEOPARDOUSLY
JEOPARDS
JEOPARDY
JEOPARDYING

23 words start with JEO.