Yes, FIDELITY is a Scrabble word!

Letter values in Scrabble US: F 4, I 1, D 2, E 1, L 1, I 1, T 1, Y 4.

Is it a valid word?

FIDELITY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

accuracy with which an electronic system reproduces the sound or image of its input signal
the quality of being faithful