The kanji 宇 is not commonly used by itself in everyday words. It mainly appears in proper names (people, places) and in the compound 宇宙うちゅう (“universe / space”).

• 宇宙うちゅう — universe / outer space
• 宇宙飛行士うちゅうひこうし — astronaut
• 宇宙船うちゅうせん — spacecraft
• 宇都宮うつのみや — Utsunomiya (place name, family name)
• 宇野うの — Uno (family name, place name)
• 宇田うだ — Uda (family name, place name)

宇 uses 宀 (roof) to suggest a broad covering — an expanse or “house” over all. Paired with 宙 it forms 宇宙 (universe).