Word origins

• opistho-in the back, behind, rear, posterior
• opisthocranionThe posteriormost point in the midsagittal plane of the occiput
• opisthodomosA porch at the rear of a temple, set against the blank back wall of the cella.
• opisthognathidAny in the family Opistognathidae of jawfishes.
• opisthokontAny of very many eukaryotes, including animals and fungi, whose flagellate cells (if any) propel themselves with a single posterior flagellum.
• opisthosphendoneA plain or ornamented band of fabric, broad in the middle and narrow at the ends, and fastened in the front, used in Ancient Greece to support the hair behind the head.
• opodeldocA kind of plaster, said to have been invented by Mindererus, used for external injuries.
• OponeAn ancient city in Ras Hafun, in modern-day Somalia; modern Hafun.
• -opsiaForming compound nouns denoting specific deficiencies of sight.
• opsiblasticExhibiting a period of dormancy before starting to develop.
• opsigamymarriage at an old age
• OpsikionA Byzantine theme (military-civilian province) located in northwestern Asia Minor (modern Turkey).
• opsimathA person who learns late in life.
• -opsisSynonym of -opia (“seeing”).
• opsoclonusRapid, uncontrolled eye movement
• opsonIn Ancient Greek cuisine, delicacies such as cooked fish, considered an integral component of a meal.
• opsoninAny chemical produced by the body, including antibodies and complement proteins, that causes a pathogen to be more susceptible to phagocytosis.
• -opsyexamination
• opto-optical
• -oramaUsed to form, from one noun, a second meaning "wide view of" the first, or (with ironic reference to the preceding sense) "surfeit of", "overattention to", or "exaggerated praise of" the first.
• orchesisThe act and/or art of dancing.
• orchesticRelating to dance
• orchialgiaPain in the testes.
• orchotomyThe surgical removal of a testicle; castration.
• orcosUse of an oath to enhance the believability of a statement.
• orecticOf or pertaining to desire or appetite
• oreinirostralHaving a tall, domed beak or snout.
• -orexiaRelated to appetite and eating disorders.
• orexigenicThat stimulates the appetite.
• orgiastOne who attends an orgy.
• orgionAn ecstatic form of worship characteristic of some Ancient Greek mystery cults.
• OrneaeA city, mentioned in the Iliad, situated north of Leontio in Corinthia in Ancient Greece.
• ornitho-of or pertaining to birds
• ornithonAn aviary; a poultry house.
• oro-Of or pertaining to the mouth.
• oroideAn alloy of copper and zinc or tin that has a gold color, used in making inexpensive jewelry.
• OrseisA naiad of a spring in Thessaly.
• orthianDenoting a type of singing at a very high pitch.
• ortho-Right angle, perpendicular.
• orthocerasAny nautiloid cephalopod mollusc of the genus Orthoceras, known only as fossils
• orthoclasticHaving cleavage planes at right angles, as in orthoclase.
• OrthocorybantianSynonym of Massagetean.
• orthodoxiaCorrect praise; correct faith.
• orthoepyThe study of pronunciation.
• OrthogonianA member of the Orthogonian society, a social club at Whittier College founded by Richard M. Nixon in opposition to the wealthy elites at Whittier.
• orthogoniumright-angled triangle
• orthomorphicconformal
• orthopediaThe branch of medicine which deals with the prevention and correction of deformities in bodies; orthopedics.
• orthopnoeaShortness of breath when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair.
• orthostatAn upright stone or slab, especially one which is part of a larger structure.
• orthostatesSynonym of orthostat
• orthotoneRetaining the accent independently; not enclitic; said of certain indefinite pronouns and adverbs when used interrogatively, which are enclitic in other situations.
• orthotonosmuscular rigidity associated with tetanus
• orthrosThe divine office or service at dawn.
• OrthrusA two-headed dog who guarded Geryon's cattle and was killed by Heracles.
• oryctereThe aardvark.
• orycticsThe branch of geology relating to fossils.
• oryctographyThe description of fossils.
• osmazomeA substance formerly supposed to impart the characteristic meaty smell and taste to certain dishes.
• osmeteriumOne of a pair of scent organs in the larvae of certain swallowtail butterflies.
• -osmiaSmell; odour.
• osmicPertaining to, derived from, or containing, osmium; specifically, designating those compounds in which it has a higher valence.
• osmidrosisBody odour.
• osmo-osmosis
• osphresiolagniaSexual arousal through olfactory stimulation.
• OsroeneAn ancient Syriac kingdom, Roman province and historical region in northwestern Mesopotamia in modern Turkey and Syria, which enjoyed semi-autonomy to complete independence from the years of 132 B.C.E. to 244 C.E..
• osseoaponeuroticPertaining to an object composed of bone and aponeurosis; at the end of a muscle where it becomes tendon.
• osteo-bone
• osteoclasyThe surgical fracture and resetting of a bone.
• osteocollaA kind of glue obtained from bones.
• osteonAny of the central canals, and surrounding bony layers, found in compact bone.
• ostracodAny of many small crustaceans, of the class Ostracoda, that resemble a shrimp enclosed in a bivalve shell.
• ostraconA piece of pottery or stone, usually broken off from a vase or other earthenware vessel, especially one used to cast a vote during the Ancient Greek process of ostracism.
• -otA demonymic suffix mostly found in borrowings from Greek.
• ot-ear
• otacousticonAn instrument to aid hearing, such as an ear trumpet or hearing aid.
• otapostasisThe condition of abnormally protruding ears
• otarySynonym of eared seal.
• -oteHaving or equipped with a certain feature or structure.
• otheoscopeAn instrument for exhibiting the repulsive action produced by light or heat in a vacuum; a modification of the radiometer.
• otocinclusAny member of the species of small South American freshwater fish of the genus Otocinclus, popular in home aquariums.
• otocraneThe bony labyrinth.
• otopetrinAny of a group of transmembrane proteins associated with otoconia and with sensing the sour taste
• oulorrhagiaBleeding from the gums.
• OuranosSynonym of Uranus.
• OureaThe primordial gods of the mountains in Greek mythology
• ousiaThe essential nature or ‘substance’ of God, often as contrasted to the ‘energies’ (external actions and influences) through which he is manifest.
• oxeaa monoaxial spicule which is pointed at both ends
• oxy-Sharp, keen, acute, pungent, acid
• oxycrateA mixture of water and vinegar.
• oxynticProducing acid.
• oxytocicServing to promote uterine contractions, thus accelerating childbirth.
• oxytoneHaving the stress on the last syllable.
• oxytonesisThe shift of accent to the final syllable.
• ozadeneA defensive gland present in some arthropods, which secretes a foul-smelling substance to discourage predators.
• ozaenaAn atrophic type of chronic non-specific rhinitis characterized by a foul odor from the nose, now considered rare.
• ozænicOf or pertaining to ozænæ.
• ozoporeThe opening of a defensive gland present in some arthropods, which secretes a foul-smelling substance to discourage predators.
• pachnoliteA monoclinic-prismatic mineral containing aluminum, calcium, fluorine, hydrogen, oxygen, and sodium.
• PachonThe ninth month of the later ancient Egyptian civil calendar and Coptic calendar, corresponding to the first month of the season of Shemu. Since 25 BCE, when the calendar was reformed to include leap-days, Pachon has been in roughly May.