singleton

noun
1
a single item of the kind that you are talking about
تک, واحد, یکه, یه‌دانه, تنها واحد, منفرد
2
a person who is not married or in a romantic relationship
مجرد, فرد مجرد, غیرمتاهل
3
a person or an animal that is not a twin, etc.
تک‌قلو, فرزند تنها