Feminine variant of Ernest, from Germanic 'ernst' meaning 'serious, resolute.' A Southern American elaboration.
Earnistine is another feminine offshoot of Ernest, shaped by the same Germanic root meaning serious or resolute, but given a more elaborate and distinctly Southern American feel. The name stretches the solid core of Ernest into a more ornate and romantic form.
That makes it sound both family-rooted and inventive, as if it grew through use rather than design. It has the kind of name history that often lives in extended family lines: part virtue, part tribute, part style. Earnistine feels formal, memorable, and a little antique, but also warm and personal.
The longer shape gives it a house-name grace, while the meaning keeps it earnest in the literal sense. It is unusual, yet it still carries the reassuring backbone of a familiar classic.