Our orbit could bes be described as an oval.
If by revolution you mean the spin on it's own axis this is more or less a perfect circle. If you are referring to it's orbit around the sun, this is elliptical, not a perfect circle.
A year.
Seasons
we call it revolution.
Gravity.
the revolution of earth around the sun
REVOLUTION
Ellipse.
Yes.
Earths tilted axis and its revolution around the sun
the heliocentric system and the geocentric system
Orbit