n. 1. Zoology a. An elongated flexible unsegmented extension, as one of those surrounding the mouth of a sea anemone, used for feeling, grasping, or locomotion.
b. One of these structures in a cephalopod, typically being retractile and having a clublike end usually with suckers or hooks, in contrast to an arm, which is nonretractile and typically has suckers along the underside.
2. Botany One of the sensitive hairs on the leaves of certain insectivorous plants, such as a sundew.
3. A similar part or extension, especially with respect to the ability to extend influence, activity, or control: an espionage network with far-reaching tentacles.