A puffer-fish, going out of business?
Literally: non – together – “be crowned with” / “live under” – sky
Alternately: A hated enemy; deep and abiding antipathy toward someone. Someone you despise so much that you can’t bear to live under the same sky as them.
This compound may also be read as a regular Japanese sentence, 「俱に天を戴かず」 (tomo ni ten wo itadakazu), “not putting the heavens overhead together.” The four-character version may also be followed by ～の間柄 (-no aidagara), “a relationship of (unquenchable hatred).”
Switching the first two characters (俱不戴天, gu fu tai ten) is a rare but acceptable alternative, as is replacing 俱 with 同 (dou), “same.” But it would be an error to replace 俱 with its cousin and homophone 具, “tool,” or 戴 with lookalike 載 (sai, “ride”).
This phrase comes to us from our friend, the Book of Rites (Japanese 『礼記』 = Raiki). It comes from a section that seems to be describing the proper attitude toward the enemies of one’s friends and family; the specific nuance of this phrase is how you feel about your father’s enemy, where (e.g.) the enemy of one of your friends is merely not to be tolerated within the same country, rather than the same world.