The kanji 酷 primarily conveys the idea of "cruel," "severe," "harsh," or "extreme." It suggests a state of being excessively intense or causing suffering. It can also imply something is very serious, intense, or over the top.

・On-yomi (音読み): コク ・Kun-yomi (訓読み): ひど（い）

⚫︎ 残酷酷な映画 Translation: A cruel/brutal movie ⚫︎ 酷酷暑 Translation: Extreme heat ⚫︎ 彼は酷酷い仕打ちを受けた Translation: He received harsh treatment.

The kanji 酷 is a phono-semantic compound (形声文字, けいせいもじ). The left side is a radical called 酉 (とり - bird/alcohol vessel) and is a semantic component representing something related to wine or intoxication. The right side is 告 (こく - to inform/tell) and is a phonetic component, representing the sound "ko(ku)". Originally, 酷 may have described the intense effects of strong alcohol. Over time, the meaning expanded to encompass the broader concept of "extreme" or "cruel". The implication is something that overwhelms the senses, similar to the powerful effects of alcohol.