Answer: vastest

AnswerCrossword Clue
VASTEST

Most expansive

VASTEST

Encompassing the most space

VASTEST

Most extensive

VASTEST
Most immense.
VASTEST
Most enormous.
VASTESTLargest in scope
VASTESTMost widespread
VASTESTLike Russia, of all countries
VASTESTMaximally massive
VASTESTMost immense