na-adjective, noun
Used when a demand, condition, treatment, judgment, or situation is harsh to the point of feeling cruel or unfair. As a noun it is more limited and often appears in formal set phrases such as 酷を極める.
失敗したばかりの彼にそれを言うのは酷だ。
It would be harsh to say that to him right after he failed.
新人にこの量の仕事を任せるの
It is unfair to put this much work on a newcomer.
当時の労働環境は酷を極めた。
The working conditions at the time were extremely harsh.
A much more common i-adjective meaning awful, terrible, or cruel; broader and more everyday than 酷 read こく.
Means strict, severe, or demanding, but does not necessarily imply cruelty or unfairness.
Specifically means cruel or brutal, especially toward people or living things; stronger and more explicit than 酷.
A Sino-Japanese word using the on-reading こく of 酷. The spelling is conventionally associated with severity, harshness, or cruelty; the precise historical development is not specified.