[1] : The Collaborative International Dictionary of English v.0.48

abatis \ab"atis\, abattis \aba"ttis\, a^b".ati^s;
   french .a`b.a`t=e" n. f. abatis, abattis, mass of
   things beaten or cut down, fr. abattre. see abate. fort.
   a means of defense formed by felled trees, the ends of whose
   branches are sharpened and directed outwards, or against the
   enemy.
   1913 webster
see also:
abate 

[2] : WordNet (r) 2.0

abatis
     n : line of defense consisting of a barrier of felled or live
         trees with branches sharpened or with barbed wire
         entwined toward the enemy syn: abattis
see also:
abattis 

[3] : Moby Thesaurus II by Grady Ward, 1.0

56 moby thesaurus words for "abatis":
   advanced work, balistraria, bank, banquette,
   barbed-wire entanglement, barbican, barricade, barrier, bartizan,
   bastion, battlement, breastwork, bulwark, casemate,
   cheval-de-frise, circumvallation, contravallation, counterscarp,
   curtain, demibastion, dike, drawbridge, earthwork, enclosure,
   entanglement, escarp, escarpment, fence, fieldwork, fortalice,
   fortification, glacis, loophole, lunette, machicolation, mantelet,
   merlon, mound, outwork, palisade, parados, parapet, portcullis,
   postern gate, rampart, ravelin, redan, redoubt, sally port, scarp,
   sconce, stockade, tenaille, vallation, vallum, work

[4] : THE DEVIL'S DICTIONARY ((C)1911 Released April 15 1993)

abatis, n.  rubbish in front of a fort, to prevent the rubbish outside
from molesting the rubbish inside.

Abatis >> A Words
Abatis, definition of term: Abatis
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