"Eighthly" is a word in ENGLISH

An acetabulum; or about one eighth of a pint.

A vinegar cup; socket of the hip bone; a measure of about one eighth of a pint, etc.

The eighth month of the year, containing thirty-one days.

A horse, not of pure breed, but having only one eighth or one sixteenth impure blood in his veins.

Accord or agreement of sounds produced simultaneously, as a note with its third, fifth, and eighth.

of judicial proceedings. The title of the second part of the Digests or Pandects, including the fifth, sixth, sev-enth, eighth, …

of testaments. The title of the fifth part of the Digests or Pandects; comprising the twenty-eighth to the thirty-sixth books, …

Pertaining to the scale of eight tones, the eighth of which is the octave of the first.

A weight; in Apothecaries' weight, one eighth part of an ounce, or sixty grains; in Avoirdupois weight, one sixteenth part …

The eighth after the tenth.

Next in order after the seventh.

The interval of an octave.

Consisting of one of eight equal divisions of a thing.

The quotient of a unit divided by eight; one of eight equal parts; an eighth part.

A subordinary, resembling the pale, but of one fourth its width (according to some writers, one eighth).

In old English law. The fourth part of a yard-land. Noy says an eighth only, because, according to hlm, two …

The breadth of a finger, or the fourth part of the hand; a measure of nearly an inch; also, the …

A furlong, or a furrow one-eighth part of a mile long. Co. Litt 5b

A measure of length; the eighth part of a mile; forty rods; two hundred and twenty yards.

A measure of length, be-lng forty poles, or one-eighth of a mile