Feeler

Part of speech: noun (n.)

1. One who, or that which, feels.

2. One of the sense organs or certain animals (as insects), which are used in testing objects by touch and in searching for food; an antenna; a palp. Insects . . . perpetually feeling and searching before them with their feelers or antennæ. Derham.

3. Anything, as a proposal, observation, etc., put forth or thrown out in order to ascertain the views of others; something tentative.