axis
axis of incidence

eccentric
eccentric axis

imaginary
imaginary axis

major
major axis

on
the Earth turns on its axis

optical
optical axis

polar
polar axis

principal
principal axis

reference
reference axis

revolve
...on its axis

semi-axis
semieixo

slope
the slope of the Earth's axis

swing
to swing on an axis

swing around
to swing round an axis

swing round
to swing round an axis

transverse
transverse axis

x-axis
eixo das abcissas

y-axis
eixo das ordenadas