feeler (n.)

• advance
• antenna
• approach
• barb
• barbel
• barometer
• bid
• catechism
• cross-question
• demand
• foretaste
• hint
• inquiry
• interrogation
• interrogative
• interrogatory
• invitation
• issue
• leader
• leading
• offer
• offering
• overture
• presentation
• probe
• problem
• proffer
• query
• question
• quodlibet
• sample
• sensor
• sound
• sounder
• submission
• suggestion
• test
• tester
• topic
• vibrissa
• weathercock