octarius

Etymology
From.

Noun

 * 1)  the pint (eighth of a gallon) in the apothecaries' system

Etymology
From oct- (as in and ), due to it being an eighth part of a gallon. Likely modeled after, from , used in Classical Latin as the name of a unit of volume (the sester) equivalent to a sixth of a Latin ; compare also , another volume measure in Ancient Roman units of measurement. However, strict analogy with would have required the use of the form  instead.

Noun

 * 1)  the pint (eighth of a gallon) in the English apothecaries' system
 * 2) * {{Q|la||Pharmacopoeia Collegii regalis medicorum Londinensis M.DCCC.IX.|year=1809|quote=Mensura etiam liquidorum dispar est, alia cerevisiae, alia vino propria; posteriorem nos adhibemus, mensurisque liquidorum utimur ex congio vinario deductis. Congius vinarius legibus regni definitus est, quem ad usus medicinales sic dispertimus: videlicet, Congius } habet { Octarios octo, O Octarius } habet { Fluiduncias sedecim, f℥ Fluiduncia } habet { Fluidrachmas octo, fʒ Fluidrachma } habet { Minima sexaginta, ♏︎  Notas apposuimus, quibus quamque mensuram designamus.  Ne quis error nascatur ex nominibus, quae ponderibus et mensuris nullo discrimine imposita sunt, nova quaedam finximus non inconsultè, quae brevis usus reddet facilia.|trans=The measures of liquids also differ, one being used for beer, and another for wine; we adopt the latter, and employ for liquids, measures which are derived from the wine gallon. The wine gallon is defined by the statutes of the realm, and we divide it for medical purposes in the following manner, viz.  The gallon Cong. } contains { eight pints O The pint } contains { sixteen fluidounces ƒ℥ The fluidounce } contains { eight fluidrachms ƒʒ The fluidrachm } contains { sixty minims ♏︎  We have added the signs by which we denote the several measures.  That no error may arise from the indiscriminate use of the same terms to express both weights and measures, we have, after due consideration, devised certain new ones, which use will in a short time render easy.|transauthor=Richard Powell|transyear=1815|refn= }}

Usage notes
Used by pharmacists in the United Kingdom and United States of America from the 19th through the 20th century. Aside from $\langleoctarius\rangle$,   the form $\langleoctavius\rangle$   (not to be confused with the previously existing proper noun Octavius) came to be used with the same meaning; the latter may have originated as a misspelling or misreading of the former as they differ in only one letter and cursive minuscule r resembles v. The form may have been alternatively derived (or reinterpreted as being derived) from.