No.
You can add a capacitor at the input of the A/D pin but this will slow things down but not stop them from changing.
Every analog signal has electrical "noise" on it. The trace depicts noise on a signal. When the A/D converter "reads" the signal some of that noise gets factored in. It can be reduced but cannot be eliminated.
This is why the world has gone to mostly digitized signals.
If you absolutely need a stable signal, look into encoders.
