Definify.com

Webster 1913 Edition

adv.

In an immeasurable manner or degree.

“Immeasurably distant.”

Wordsworth.

adv.

To an extent not to be measured; immensely; beyond all measure.

immeasurably ‎(not comparable)

In a manner that is not measurable, in a way that can not be measured.
The sky seems immeasurably large at night.