• 字じ — character / letter
• 文字もじ — written character
• 漢字かんじ — kanji / Chinese character
• 名字みょうじ — family name / surname
• 数字すうじ — number / numeral
• 赤字あかじ — deficit / in the red

More examples ▼

• 誤字ごじ — typo / miswritten character
• 活字かつじ — printed type
• 字幕じまく — subtitles / captions
• 黒字くろじ — surplus / in the black
• 十文字じゅうもんじ — cross shape

“字” originally pictured a child learning under a roof, which later came to represent written characters. Today, it is central to words related to writing systems, names, numbers, and subtitles.