A tentative suggestion designed to elicit the reactions of others. Generally "feeler" is a term used when selling something when the seller isn't sure if they want to sell it or keep it. They might post an ad saying with the forewarning, feeler, when they are on the fence about getting rid of something to see people's response and offers. Many times feelers are put up for sale and sold, but sometimes the owner decides to keep.
It's essentially like putting your toes in the water to feel the temperature before jumping in all the way. Sometimes we get in, sometimes we don't.
Feeler: 2005 Subaru STi with tasteful mods 35k NJ