Definition of "tentacle"

With one blow of the axe, Captain Nemo cut this formidable tentacle, that slid wriggling down the ladder.

1873, Jules Verne, “The “Devil Fish.”—Terrible Encounter.—Crushed to Death in the Arms of a Monster.—Ned Land saved by the Captain.—“Only Revenge”.”, in [anonymous], transl., Twenty Thousand Leagues under the Seas; […], James R. Osgood edition, Boston, Mass.: Geo[rge] M[urray] Smith & Co., part II, page 274

The body was small, but fitted with two bunches of prehensile organs, like long tentacles, immediately under the mouth.

1897, H. G. Wells, The Crystal Egg

Surmounting this head were four slender grey stalks bearing flower-like appendages, whilst from its nether side dangled eight greenish antennae or tentacles.

1936, H. P. Lovecraft, The Shadow Out of Time

New extensions into the outer London dormitory areas also have been constructed, and at the present moment the tentacles of London's Underground are slowly but surely extending eastwards into Essex to relieve congestion on the suburban lines of the former Great Eastern Railway.

1948 January and February, C. R. L. Coles, “The Grouping Era”, in Railway Magazine, page 21

A joint RAF/Army staffed Air Support Control (ASC) headquarters was established at each army corps and each armoured division, linked to the forward brigades by a 'tentacle' equipped with two-way wireless telegraphy.

2013, Dr Ian Gooderson, Air Power at the Battlefront, page 26