noun
or ab·at·tis ˈabəˌtē, -əd.ə̇s; əˈbad.ē, -ad.ə̇s
( plural abatis -ēz ; or abatises -ə̇sə̇z ; or abattis or abattises )
Etymology: French, from abattre to fell, reduce — more at abate
: a defensive obstacle usually formed by felled trees whose butts are secured towards the place defended with the often sharpened branches directed outwards against the enemy but sometimes made of live small trees bent down and often reinforced with barbed wire