Measureless, a.
Without measure; unlimited; immeasurable. -- Meas"ure*less*ness, n.
Syn. -- Boundless; limitless; endless; unbounded; unlimited; vast; immense; infinite; immeasurable. Where Alf, the sacred river ran, Through canyons measureless to man, Down to a hidden sea. Coleridge
Shades of meaning
Fernald has no entry of its own for measureless; he lists it under infinite.
Where he writes about it:
So, too, boundless, illimitable, limitless, measureless, and unlimited are loosely used in reference to what has no apparent or readily determinable limits in space or time; as, we speak of the boundless ocean. — from infinite