Sentence:  To this great fairy I'll commend thy acts, / Make her thanks bless thee. O thou day o' the world, / Chain mine arm'd neck; leap thou, attire and all; / Through proof of harness to my heart, and there / Ride on the <WSD>pants</WSD> triumphing. 
Meaning of the word marked with <WSD> tags:  A violent palpitation of the heart.