Yes, STROKE is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, R 1, O 1, K 5, E 1.

Is it a valid word?

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

(sports) the act of swinging or striking at a ball with a club or racket or bat or cue or hand
the maximum movement available to a pivoted or reciprocating piece by a cam
a sudden loss of consciousness resulting when the rupture or occlusion of a blood vessel leads to oxygen lack in the brain
a light touch
a light touch with the hands
(golf) the unit of scoring in golf is the act of hitting the ball with a club
the oarsman nearest the stern of the shell who sets the pace for the rest of the crew
anything that happens suddenly or by chance without an apparent cause
a punctuation mark (/) used to separate related items of information
a mark made on a surface by a pen, pencil, or paintbrush
any one of the repeated movements of the limbs and body used for locomotion in swimming or rowing
a single complete movement

Also: cam stroke, cerebrovascular accident, chance event.

Not playable in Scrabble US: CVA, SEPARATRIX.