N. & Q. Notes and Queries.
O. Ohio; Oxygen.
O/A. On account of.
OB., _obiit_=Died.
OB., OBAD. Obadiah.
OBDT. Obedient.
OBJ. Object, Objective.
OBL. Oblique; Oblong.
OBS. Observation; Obsolete.
OBSTET. Obstetrics.
OC. Ocean.
O.C.R. Order of Corporate Reunion.
OCT. October.
O.D. Ordnance Data.
O.E. Old English.
O.F. Odd Fellow; Old French.
OFF. Official.
O.H.G. Old High German.
O.H.M.S. On His (or Her) Majesty's Service.
O.K. All correct (prob. a humorous spelling of this).
OLD TEST. Old Testament.
O.M. Old Measurement.
OMN. HOR., _omni hora_=Every year.
ONOMAT. Onomatopoeia.
O/O. Percent.
O.P. Old Price; _Ordinis Praedicatorum_=Of the Order of Preachers (or Dominicans).
O.P. Out of Print.
OP. Opera.
OP. Opposite; _Opus_=Work.
OP. CIT., _opere citato_=In the work cited.
ORD. Ordained; Order; Ordinary; Ordnance.
OR. Oregon.
O.S. Old Style.
O.S.A., _Ordinis Sancti Augustini_=Of the Order of St Augustine.
O.S.B., _Ordinis Sancti Benedicti_=Of the Order of St Benedict.
O.S.F., _Ordinis Sancti Francisci_=Of the Order of St Francis.
O.T. Old Testament.
OXF. Oxford.
OXON., _Oxonia_=Oxford;--_Oxoniensis_=Of Oxford.
OZ. Ounce.
P. Page; Participle;--P.A., Participial adjective.
PA., also PENN. Pennsylvania.
PAC. OC. Pacific Ocean.
PAINT. Painting.
PAL. Palestine; Palaeontology.
PAM. Pamphlet.
PAN. Panama.
PAR. Paragraph; Parallel; Parish.