Unremitting, a.
Not remitting; incessant; continued; persevering; as, unremitting exertions. Cowper. -- Un`re*mit"ting*ly, adv. -- Un`re*mit"ting*ness, n.
Shades of meaning
Fernald has no entry of its own for unremitting; he lists it under continual.
He lists it without comment; the entries above explain its neighbors.