tentacle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An elongated flexible unsegmented extension, as one of those surrounding the mouth of a sea anemone, used for feeling, grasping, or locomotion.
• noun 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.
• noun Botany One of the sensitive hairs on the leaves of certain insectivorous plants, such as a sundew.
• noun A similar part or extension, especially with respect to the ability to grasp or stretch.

from The Century Dictionary.

• noun In zoology, some or any elongated and comparatively slender or flexible process or appendage of an animal, used as an organ of touch, or for exploration, prehension, and sometimes locomotion; a feeler; a tentaculum.
• noun In botany, a kind of sensitive hair or filament, such as the glandular hairs of Drosera.
• noun Figuratively, anything resembling a tentacle; a feeler.
• noun See the adjectives.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A more or less elongated process or organ, simple or branched, proceeding from the head or cephalic region of invertebrate animals, being either an organ of sense, prehension, or motion.
• noun (Zoöl.) a sheathlike structure around the base of the tentacles of many mollusks.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An elongated, boneless, flexible organ or limb of some animals, such as the octopus and squid.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun something that acts like a tentacle in its ability to grasp and hold
• noun any of various elongated tactile or prehensile flexible organs that occur on the head or near the mouth in many animals; used for feeling or grasping or locomotion