The rules that use the vocabulary item "amphibious" are:

<a_a_v>

amphibious assault vehicle

amphibious assault vehicles

<type_of_ship-sing>

amphibious assault ship

amphibious transport dock

<type_of_ship>

amphibious assault ship

amphibious assault ships

amphibious transport dock

amphibious transport docks

<a_a_v-pl>

amphibious assault vehicles

<type_of_ship-pl>

amphibious assault ships

amphibious transport docks

<a_a_v-sing>

amphibious assault vehicle