unmarried or not in a relationship

अविवाहित

English Usage: He has been single for years and enjoys his independence.

Hindi Usage: वह सालों से अविवाहित है और अपनी स्वतंत्रता का आनंद लेता है।

one alone; individual

one only; not accompanied by others

isolated or alone in its category

विशिष्ट

English Usage: He had a single focus on his project, ignoring all distractions.

Hindi Usage: उसका प्रोजेक्ट पर एक विशिष्ट ध्यान था, उसने सभी व्याकुलताओं की अनदेखी की।