An expletive expressing anger or frustration (vulgar). Used as a strong swear like “damn it” or “son of a bitch.”
ちくしょう、電車に乗り遅れた。
Damn it — I missed the train.
大会で負けて、ちくしょうとしか言えなかった。
I lost at the tournament and could only say, 'damn it.'
ちくしょう！あいつ、また約束を破った。
Damn it! He broke his promise again.
An animal or beast (older/archaic usage). Can refer to beasts or animals in general.
昔話の中では、畜生が人と話す場面もある。
In old folk tales, beasts are sometimes depicted talking with people.
山中には様々な畜生が生息している。
Various animals live in the mountains.
In Buddhism, a being reborn in the animal realm (one of the six realms), i.e. a life dominated by instinct and suffering.
仏教では、悪業の結果として畜生に生まれ変わることがあると説かれる。
Buddhism teaches that, as a result of bad karma, one can be reborn as an animal (in the animal realm).
A derogatory noun used to insult someone — 'brute' or 'bastard' (vulgar).
畜生め、俺の席を勝手に取るとは許せない。
You bastard — I won't forgive you for taking my seat without permission.
そんな畜生なことをするな。
Don't do such a cruel/mean thing, you jerk.