extra/extro

outside, beyond

Spelled extra, extro · extra 'outside, beyond'; extro- is a later reshaping modeled on intro-.

Latin extra meant outside: extraneous details fall outside the subject, extravagant spending wanders beyond limits, and an extrovert turns outward.

Words built from it

extraneous — Unrelated to what matters or is needed.
extra- (outside) + -aneous (relating to)
extrapolate — Estimate beyond known information by extending its pattern.
extra- (beyond) + -polate (estimate; modeled on interpolate)
extravagant — Spending or using far more than is reasonable.
extra- (beyond) + vag (wander) + -ant (doing)
extrovert — A person who tends to seek social interaction and outward activity.
extro- (outside) + vert (turn)
extraordinary — Very unusual or remarkable.
extra- (outside) + ordinary (usual order)
extracurricular — Outside the regular course of school studies.
extra- (outside) + curricular (relating to school studies)
extrasensory — Said to involve perception beyond the ordinary senses.
extra- (beyond) + sensory (relating to the senses)

extraction — From Latin ex- (out) + trahere (pull), through extractus. Its opening letters cross the boundary between ex- and tract-.