1. A test of public opinion 
2. A balloon sent up to test air currents

Derived forms: trial balloons

Type of: balloon, dummy run [Brit], test, trial, trial run, tryout

Encyclopedia: Trial balloon

• overdramatize
• overdraw
• overdress
• overdressed
• overdrive
• overdub
• overdue
• overeager
• overeat
• overeating
• overemotional
• overemphasis
• overemphasise
• overemphasize
• overenthusiastic
• overestimate
• overestimation
• overexcite
• overexcited
• overexert
• overexert oneself
• overexertion
• overexploit
• overexploitation
• overexpose