_O._, _octarius_, a pint. _Ol. lini s. i._, _oleum lini sine ligné_, cold-drawn linseed oil. _Omn. hor._, _omni horâ_, every hour. _Omn. bid._, _omni biduo_, every two days. _Omn. bih._, _omni bihorio_, every two hours. _O. M._, or _omn. man._, _omni mane_, every morning. _O. N._, or _omn. noct._, _omni nocte_, every night. _Omn. quadr. hor._, _omni quadrante horæ_, every quarter of an hour. _O. O. O._, _oleum olivæ optimum_, best olive oil. _Ov._, _ovum_, an egg. _Oz._, the ounce avoirdupois. _P. æ._, _part. æqual._, _partes æquales_, equal parts. _P. d._, _per deliquium_, by deliquescence. _Past._, _pastillus_, a pastil, or ball of paste. _P._, _pondere_, by weight. _Ph. D._, _Pharmacopœia Dubliniensis_. _Ph. E._, _Pharmacopœia Edinensis_. _Ph. L._, _Pharmacopœia Londinensis_. _Ph. U. S._, _Pharmacopœia of the United States_. _Part. vic._, _partitis vicibus_, in divided doses. _Per. op. emet._, _peractâ operatione emetici_, the operation of the emetic being over. _Pocul._, _poculum_, a cup. _Pocill._, _pocillum_, a small cup. _Post sing. sed. liq._, _post singulas sedes liquidas_, after every loose stool. _Ppt._, _præparata_, prepared. _P. r. n._, _pro re nata_, occasionally. _P. rat. ætat._, _pro ratione ætatis_, according to the age. _Pug._, _pugillus_, a pinch, a gripe between the thumb and the two first fingers. _Pulv._, _pulvis_, _pulverizatus_, a powder, pulverised. _Q. l._, _quantum lubet_, } as much as you _Q. p._, _quantum placet_,} please. _Q. s._, _quantum sufficiat_, as much as may suffice. _Quor._, _quorum_, of which. _Q. V._, _quantum vis_, as much as you will. _Red. in pulv._, _redactus in pulverem_, reduced to powder. _Redig. in pulv._, _redigatur in pulverem_, let it be reduced into powder. _Reg. umbil._, _regio umbilici_, the umbilical region. _Repet._, _repetatur_, or _repetantur_, let it, or them, be repeated. _S. A._, _secundum artem_, according to art. _Scat._, _scatula_, a box. _S. N._, _secundum naturam_, according to nature. _Semidr._, _semidrachma_, half a drachm. _Semih._, _semihora_, half an hour. _Sesunc._, _sesuncia_, half an ounce. _Sesquih._, _sesquihora_, an hour and a half. _Si n. val._, _si non valeat_, if it does not answer. _Si op. sit_, _si opus sit_, if it be necessary. _Si vir. perm._, _si vires permittant_, if the strength allow it. _Signat._, _signatura_, a label. _Sign. n. pr._, _signetur nomine proprio_, let it be written upon, let it be signed with the proper name (not the trade name). _Sing._, _singulorum_, of each. _S. S. S._, _stratum super stratum_, layer upon layer. _Ss._, _semi_, a half. _St._, _stet_, let it stand; _stent_, let them stand. _Sub fin. coct._, _sub finem coctionis_, towards the end of boiling, when the boiling is nearly finished. _Sum. tal._, _sumat talem_, let the patient take one such as this.