Geometry, an age-old branch of mathematics, concerns itself with questions of size, shape, relative positions of figures, and properties of space.

While it’s a vast topic with myriad terms, today, we’ll journey through the niche of those that begin with the letter ‘O’.

Here we go:

## Geometry Words Starting In O

**Obtuse angle**– An angle greater than 90° but less than 180°.**Origin**– A fixed reference point from which distances or angles are measured.**Oval**– A shape resembling an egg or an ellipse.**Octagon**– A polygon with eight sides and eight angles.**Octahedron**– A polyhedron with eight faces.**Orthogonal**– Being perpendicular or relating to right angles.**Orthocenter**– The point where the altitudes of a triangle intersect.**Orbit**– In geometry, it is the path a point takes around another fixed point.**Ordinate**– The vertical coordinate of a point, especially in a two-dimensional Cartesian system.**Oblique**– Neither perpendicular nor parallel; slanting.**Obliquity**– The angle between the plane of an orbit and a reference plane.**Opposite sides**– Sides that are directly across from each other in a polygon.**Octant**– One of eight sectors created when three mutually perpendicular planes intersect.**Opposite angles**– Angles opposite each other when two lines intersect.**Orthogonal projection**– A projection of a figure onto a plane by drawing perpendiculars from the points of the figure to the plane.**Offset**– A short distance measured perpendicular to the main direction.**Orientable**– A surface that possesses a consistent ‘up’ and ‘down’.**Octahedral angle**– The angle between any two edges of an octahedron, about 109.47°.**Outradius**– The radius of a circle circumscribed about a polygon.**Octagonal prism**– A prism with octagonal bases.**Ogee curve**– An S-shaped curve.**Obelisk**– A tall, four-sided pillar that tapers upwards and ends in a pyramid.**Obtuse triangle**– A triangle with one obtuse angle.**Outer circle**– The circumscribed circle that touches all vertices of a polygon.**Octal system**– A base-8 number system, not strictly geometrical but used in certain geometrical computations.**Octagonal pyramid**– A pyramid with an octagonal base.**Order**– In geometry, it often refers to the number of times a geometric object intersects another.**Orientation**– The arrangement or alignment of a shape in relation to its surroundings or another shape.**Outlier**– A point or value that differs substantially from others in a data set.**Orthonormal**– Describes a set of vectors that are both orthogonal and normalized.**Osculating circle**– A circle that touches a curve at a point and has the same curvature as the curve at that point.**Octadic**– Pertaining to the number eight, as in an octadic angle division.**Orthodiagonal**– Pertaining to a quadrilateral where the diagonals are perpendicular.**Osculation**– The act of fitting a curve to another curve or surface.**Octahedral symmetry**– The symmetry operations that preserve an octahedron.**Overshoot**– The amount a curve or surface extends beyond its expected end or limit.**Orbifold**– A generalization of manifolds allowing for certain singularities.**Orthogonal transformation**– A linear transformation that preserves lengths.**Optical geometry**– A system that describes how light rays propagate in a linear fashion.**Obtuse hyperbola**– A hyperbola where the angle between the asymptotes is obtuse.**Obtuse parabola**– A term occasionally used to describe certain configurations in parabolic geometry.**Octadecagon**– An 18-sided polygon.**Octonion**– A kind of non-associative algebra over the real numbers.**Optimal design**– The study of designing experiments.**Orthogonal matrix**– A square matrix whose rows and columns are orthogonal vectors.**Orthonormal basis**– A set of vectors which are mutually orthogonal and each of unit length.**Outscribed**– Enclosing or encircling a shape, often referring to circles around polygons.**Oriented angle**– An angle that determines the rotation direction (clockwise or counterclockwise).**Octagon tessellation**– A tiling of the plane using octagons.**Octahedron tessellation**– A 3D tiling using octahedra.

While geometry might seem abstract and challenging, the beauty lies in how these concepts shape our world, both natural and constructed.

Understanding these ‘O’ terms offers a fascinating window into the complexity and artistry of this mathematical discipline. Whether you’re a seasoned geometer or a casual enthusiast, may this list serve as a bridge to deeper exploration.

**Oblique cone**– A cone that is not a right cone, meaning its apex is not aligned directly above the center of its base.**Oblate**– Flattened at the poles; usually referring to spheroids.**Octic**– Referring to the eighth degree, especially a polynomial.**Off-center**– Not positioned in the middle or not aligned.**Overlapping**– Geometric figures covering some of the same space.**Outspread**– Extended or spread out, typically referring to angles.**Obtuse sector**– The portion of a circle bounded by an obtuse angle and its associated arc.**Orthogonal complement**– A subspace where every element is orthogonal to a given subspace.**Octacontagon**– A polygon with 80 sides.**Octilinear**– Pertaining to paths or figures defined by straight lines and octagonal symmetries.**Outlying**– Positioned at a greater distance from the center.**Octadic division**– Splitting a shape or figure into eight equal parts.**Outcurve**– A curve that bends outward from a central point or line.**Oversketch**– A rough drawing over an existing geometric figure to study alterations.**Octahedral angle**– The angle made between any two adjacent edges of an octahedron.**Orthocyclic**– Circles that intersect at a single, shared point.**Orthonormal transform**– A transformation that maintains orthonormality.**Oblique prism**– A prism with bases that are not aligned directly above each other.**Octagram**– An eight-pointed star figure.**Outpolygon**– A polygon that encloses one or more other polygons.**Outangle**– An angle formed by rays extending outward from a figure or shape.**Octaplane**– A plane divided into eight regions or sectors.**Octaspace**– An eight-dimensional geometric space.**Omnioriented**– Oriented in all possible directions.**Orthogonally adjacent**– Neighboring in a manner that is aligned with the primary axes.**Oversized angle**– An angle larger than what’s typical or standard in a given context.**Oblate ellipsoid**– An ellipsoid flattened along its major axis.**Octadecahedron**– A solid figure with 18 faces.**Octant sector**– One-eighth of a circular region.**Orthogonalize**– To make vectors or functions orthogonal to each other.**Osculating plane**– The plane that touches a curve or surface at a point.**Octocycle**– A closed figure with eight straight or curved segments.**Octaedral network**– A network of lines and intersections that form octahedral patterns.**Outrigon**– An external triangle connected to another geometric shape.**Outpoint**– A point located outside a specific geometric figure.**Octagonal frustum**– The portion of an octagonal pyramid or cone between two parallel planes cutting it.**Outradius sector**– A sector formed by extending the outradius of a polygon.**Oblate cylinder**– A cylinder that’s shortened or compressed along its height.**Overslope**– A slope or incline that exceeds a specified amount.**Orthotope**– A generalization of a rectangle to higher dimensions.**Open curve**– A curve that does not return to its starting point.**Orbit curve**– The trajectory of a point under a series of geometric transformations.**Outvertex**– A vertex positioned on the exterior of a geometric shape.**Orbital ellipse**– An elliptical trajectory, particularly relevant in celestial mechanics.**Outcuboid**– An external rectangular prism associated with another 3D figure.**Orthohedron**– A 3D shape whose faces are all orthogonal to one another.**Octal segment**– One of eight parts of a divided geometric figure.**Octagonal spire**– A pinnacle or tower with eight sides, commonly seen in architecture.**Overarc**– A part of a curve that extends beyond a specified or intended endpoint.**Orthogonal hyperbola**– A hyperbola resulting from an intersection of a double cone with a plane perpendicular to its axis.

## Conclusion

Navigating the landscape of geometric terms is like exploring a labyrinth filled with patterns, symmetry, and unique structures. From the simplicity of the oval to the complexity of the octahedron, the vast world of ‘O’ terms in geometry is a testament to how intricate and profound this field of study can be.