Is an object moving in uniform circular motion accelerating?

Yes.

- - 'Acceleration' does NOT mean 'speeding up'.

It means ANY change in the speed OR direction of motion ...

speeding up, slowing down, or turning.

- - If an object is NOT moving in straight line at constant speed,

then its motion is accelerated.

- - In circular motion, or even just going around a curve,

the object is accelerating, because its direction is constantly

changing, even if its speed is constant.