Nonlinear
Ray.
a line segment
The word straight does have an antonym, which is crooked. So perhaps a crooked line is the opposite of a straight line.
In traditional sense, it is usually called "rekha" or "lakeer" in Hindi. Otherwise it remains line itself in modern cities.
for example a straight line.(is it straight up and down)
for example a straight line.(is it straight up and down)
The word "straight" as you wrote it does not contain a prefix. A prefix is a letter or group letters added on to the beginning of a word that has a meaning of its own. The word "straight" has no letters added to the beginning of it.
Word collocation
It is flat. Meaning it is just plain and straight.
direct, candid
The diameter of a circle is a straight line passing from one side to the other and through the center. It is the distance across the circle through its widest point.
Line up outside the ship.Make sure you line these up straight.