12-letter words starting with or
- oriental rug — a rug or carpet woven usually in Asia and characterized by hand-knotted pile.
- orientations — Plural form of orientation.
- orienteering — a competitive sport, originating in Sweden, that tests the skills of map reading and cross-country running, in which competitors race through an unknown area to find various checkpoints by using only a compass and topographical map, the winner being the finisher with the lowest elapsed time.
- origin story — a backstory, or established background narrative, that informs the identity and motivations of heroes and villains in a comic book or similar fictional work: The superhero’s origin story begins with a tragic accident that left him scarred, but also resulted in his supernatural powers.
- original gum — See o.g (def 1).
- original sin — Theology. a depravity, or tendency to evil, held to be innate in humankind and transmitted from Adam to all humans in consequence of his sin. inclination to evil, inherent in human nature.
- originations — Plural form of origination.
- orion nebula — a luminous nebula in the constellation Orion, in the center of Orion's sword.
- ormond beach — a town in NE Florida.
- ornamentally — In an ornamental way.
- ornithogalum — any plant of the genus Ornithogalum
- ornithomancy — Divination by means of birds, their flight, etc.
- ornithomimid — (zoology) Any member of the Ornithomimidae.
- ornithomorph — the artistic representation of a bird
- ornithophily — pollination of flowers by birds
- ornithopters — Plural form of ornithopter.
- ornithoscopy — divination from the observation of birds
- orographical — relating to the study of mountains
- oropharynxes — Plural form of oropharynx.
- ortho-cousin — parallel cousin.
- ortho-xylene — Chemistry. a clear, colorless, poisonous, flammable liquid, C 8 H 10 , the ortho isomer of xylene: used chiefly in the synthesis of phthalic anhydride.
- orthocenters — Plural form of orthocenter.
- orthoclastic — (of a crystal) having cleavages at right angles to each other.
- orthocousins — the children of two brothers or two sisters
- orthodontics — the branch of dentistry dealing with the prevention and correction of irregular teeth, as by means of braces.
- orthodontist — the branch of dentistry dealing with the prevention and correction of irregular teeth, as by means of braces.
- orthodonture — orthodontia (def 2).
- orthodox jew — a Jew who adheres faithfully to the principles and practices of traditional Judaism as evidenced chiefly by a devotion to and study of the Torah, daily synagogue attendance if possible, and strict observance of the Sabbath, religious festivals, holy days, and the dietary laws.
- orthodromics — the act or art of sailing on a great circle
- orthoformate — an ester of orthoformic acid.
- orthogenesis — Biology. Also called orthoselection. evolution of a species proceeding by continuous structural changes in a single lineage without presenting a branching pattern of descent. a theory that the evolution of a species in a continuous, nonbranching manner is due to a predetermined series of alterations intrinsic to the species and not subject to natural selection.
- orthogenetic — pertaining to or exhibiting orthogenesis.
- orthognathic — straight-jawed; having the profile of the face vertical or nearly so; having a gnathic index below 98.
- orthogonally — Mathematics. Also, orthographic. pertaining to or involving right angles or perpendiculars: an orthogonal projection. (of a system of real functions) defined so that the integral of the product of any two different functions is zero. (of a system of complex functions) defined so that the integral of the product of a function times the complex conjugate of any other function equals zero. (of two vectors) having an inner product equal to zero. (of a linear transformation) defined so that the length of a vector under the transformation equals the length of the original vector. (of a square matrix) defined so that its product with its transpose results in the identity matrix.
- orthographer — a person versed in orthography or spelling.
- orthographic — of or relating to orthography.
- orthopaedics — (used with a singular verb) the medical specialty concerned with correction of deformities or functional impairments of the skeletal system, especially the extremities and the spine, and associated structures, as muscles and ligaments.
- orthopaedist — Alternative spelling of orthopedist.
- orthopedical — (American spelling) Alternative form of orthopaedical.
- orthopterans — Plural form of orthopteran.
- orthopterist — someone who studies the Orthoptera
- orthopteroid — (zoology) Any of the insects historically included in the order Orthoptera, including the cockroaches, earwigs, praying mantises, etc.
- orthopterous — belonging or pertaining to the Orthoptera, an order of insects, including the cockroaches, mantids, walking sticks, crickets, grasshoppers, and katydids, characterized by leathery forewings, membranous hind wings, and chewing mouthparts.
- orthorhombic — noting or pertaining to a system of crystallization characterized by three unequal axes intersecting at right angles; rhombic; trimetric.
- orthosilicic — (chemistry) Of, relating to or derived from orthosilicic acid.
- orthotonesis — accentuation of a proclitic or enclitic
- orthotropism — Botany. orthotropic tendency or growth.
- orthotropous — Botany. (of an ovule) straight and symmetrical, with the chalaza at the evident base and the micropyle at the opposite extremity.
- orthovanadic — relating to orthovanadates