• 感激かんげき — deep emotion / being moved
• 激怒げきど — rage / fury
• 激戦げきせん — fierce battle
• 激減げきげん — drastic decrease
• 刺激しげき — stimulus / stimulation
• 過激かげき — extreme / radical
• 激流げきりゅう — swift current / torrent
• 激はげしい — intense / fierce

激 combines the water radical 氵 with 敫 (phonetic), evoking forceful water and, by extension, powerful motion or feeling. It’s used for strong emotions, violent actions, and rapid change.