1. Zoology. An elongated flexible unsegmented extension, as one of those surrounding the mouth or oral cavity of the squid, used for feeling, grasping, or locomotion.
2. Botany. One of the sensitive hairs on the leaves of insectivorous plants, such as the sundew.
3. A similar part or extension, especially with respect to the ability to grasp or stretch: an espionage network with far-reaching tentacles.

[New Latin tentāculum, from Latin tentāre, to feel, try. See tentative.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.