Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter. About
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abatis \ab"a*tis\, abattis \aba"t*tis\, ] (ăb"&adot;*t&ibreve;s; french &adot;`b&adot;`tē") 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.
Noun 1. line of defense consisting of a barrier of felled or live trees with branches (sharpened or with barbed wire entwined) toward the enemy (synonym) abattis (hypernym) line of defense, line of defence
Abatis Definition from Encyclopedia Dictionaries & Glossaries
An abatis, abattis, or abbattis is a field fortification consisting of an obstacle formed (in the modern era) of the branches of trees laid in a row, with the sharpened tops directed outwards, towards the enemy. The trees are usually interlaced or tied with wire. Abatis are used alone or in combination with wire entanglements and other obstacles.