1) Nightclothes 2) Nightclothes worn by men 3) Nightwear 4) Pajamas alternative 1) Nightwear 
A nightshirt is a garment intended for wear while sleeping. It is somewhat longer than most regular shirts, reaching down to the thighs or below the knees, leaving some of the legs uncovered. It is generally loose-fitting to avoid restricting the wearer`s movement while sleeping. Until the 16th century men slept naked or in a day-shirt; subsequen....
• (n.) A kind of nightgown for men. • (n.) A kind of nightgown for men.
Night'shirt` noun A kind of nightgown for men. 
A nightshirt was a garment worn for sleeping before the invention of pyjamas. The nightshirt was an exaggerated shirt with a shirt hem, but reaching to the ankles.
[n] - nightclothes worn by men
noun nightclothes worn by men
a loose shirtlike garment reaching to the knees or lower, for wearing in bed.