Is fatigue an abstract noun

No, the Word 'fatigued' is a verb, the past participle, past tense of the verb to fatigue. The past participle of the verb also functions as an adjective.

The Word 'fatigue' is both a verb and a noun.

The noun 'fatigue' is an abstract noun as a Word for mental or emotional tiredness resulting from worry or excessive work.

The noun 'fatigue' is a concrete noun as a Word for:

• physical tiredness resulting from mental or physical stress;
• weakness in a material caused by repeated stress;
• the uniform worn by members of the armed forces for physical labor.