• 呼吸こきゅう — breathing
• 呼気こき — exhalation
• 呼応こおう — coordination; response
• 呼名こめい — calling one’s name
• 呼集こしゅう — muster; gathering call
• 呼よぶ — to call; to summon

呼 combines the radical 口 (mouth) with the phonetic 乎, evoking the act of using the mouth to call out. Meanings extend to summoning and breath-related actions.

In modern Japanese it appears in everyday verbs like 呼よぶ and in medical/technical terms such as 呼吸こきゅう.

先生せんせいを 呼よんでください。
Please call the teacher.

深ふかく 呼吸こきゅうして リラックスしましょう。
Take a deep breath and relax.