- ordinary flow
- ordinary mail
- ordinary pitch
- Ordinary share
- organization chart
- organization name
- orgin
- orientability
- orientable
- orientational invariance
- oriented curve
- oriented set
- origin coordinate
- original Configuration
- original equation
- original mail
- Original Size
- orphan line
- orthmorphism
- orthocenter
- orthognal transformation
- orthogonal
- orthogonal basic
- orthogonal circles
- orthogonal complement
- orthogonal cone
- orthogonal coordinates
- orthogonal expansion
- orthogonal group
- orthogonal involution
- orthogonal matrix
- orthogonal polarization
- orthogonal process
- orthogonal projection
- orthogonal sequences
- orthogonal sets
- orthogonal substitution
- orthogonal surface
- orthogonal system
- orthogonal tests
- orthogonal trajectory
- orthogonal transformation
- orthogonalization
- orthogonalize
- orthographic projection
- orthographic view
- orthonormal polynomial
- orthonormal set
- orthonormal system
- orthonormal vectors
- orthopole
- orthoprism
- orthoptic circle
- orthoptic curve
- orthptic circle
- out-basket
- outboard record
- outbuffer subgroup
- outer
- outer density
- outer face
- outer isomorphism
- outer planet
- outfit
- outgoing call
- outgoing data
- outheader subgroup
- outlet
- outlet valve
- outline command
- outline font
- outline level
- outline map
- outline processor
- outline symbol
- outline utility
- outline view
- outlines
- output
- output alphabet
- output area
- output block
- output bound
- output buffer
- output capacity
- output card
- output channel
- output class
- output configuration
- output data
- output device
- output document
- output element
- output equipment
- output error
- output factor
- output feedback
- output field
- output file
- output filter