• 至福しふく — supreme bliss
• 至急しきゅう — urgent, immediate
• 夏至げし — summer solstice
• 冬至とうじ — winter solstice
• 必至ひっし — inevitable

The kanji 至 shows an arrow (⽮) landing precisely at a point, expressing the idea of “arriving” or “culminating.” It is used in words that reflect arrival, achievement, extremity, or finality. It’s a 5th-grade 教育漢字 and part of many idiomatic expressions in Japanese.

夏至げしは 一年いちねんで 最もっとも 昼ひるが 長ながい 日ひです。
The summer solstice is the longest day of the year.

至福しふくの 時ときを 過すごした。
I spent a moment of supreme bliss.

The kun-yomi いたる is used in standalone or descriptive phrases. The on-yomi シ is widely used in compounds, especially in abstract or advanced vocabulary related to reaching a state or degree (e.g., extreme happiness or urgency).