- octal constant
- octal digit
- octal dump
- octal notation
- octal number
- octal representation
- octal socket
- octal system
- octal tube
- octamerous
- octameter
- octan
- octandrous
- octane
- octane index
- octane number
- octane rating
- octane ratting
- octane requirement
- octane scale
- octane value
- octangle
- octangular
- octant
- octant error
- octaploid
- octarch
- octarchy
- octaroon
- octary system
- octastyle
- octastylos
- octateuch
- octavalent
- octave
- octave band
- octave device
- octave filter
- octave-flute
- octavo
- octene
- octennial
- octennially
- octet
- octette
- octigravida
- octillion
- octingentenary
- octipara
- october
- octobrist
- octocentenary
- octocentennial
- octode
- octodecimo
- octogenarian
- octogynous
- octoid
- octolateral
- octonal
- octonarian
- octonary
- octonary signaling
- octonocular
- octoped
- octopetalous
- octoploid
- octopod
- octopoda
- octopodous
- octopole
- octopus
- octoradiate
- octoroon
- octosepalous
- octosporous
- octostyle
- octosyllabic
- octosyllable
- octroi
- octrol
- octuple
- octupole
- octylene
- octyne
- ocul
- ocular
- ocular aberration
- ocular angle
- ocular crisis
- ocular estimate
- ocular gymnastics
- ocular mylasis
- ocular nystagmus
- ocular prosthesis
- ocular refraction
- ocularist
- ocularly
- oculat
- oculated