Blissful, a.
Full of, characterized by, or causing, joy and felicity; happy in the highest degree. "Blissful solitude." Milton. -- Bliss"ful*ly, adv. -- Bliss"ful*ness, n.
Shades of meaning
Fernald has no entry of its own for blissful; he lists it under happy.
He lists it without comment; the entries above explain its neighbors.