Jujutsu Kaisen features many complex kanji characters that even Japanese people rarely use! However, if you understand their meanings, you'll become a truly advanced fan!
Characters' Roles
The "Ju(呪)" is the same as the "Ju(呪)" in"Ju-On(呪怨)" that is the famous Japanese horror movie.
Others:
"術" (jutsu) has the following meanings.
Method or means: referring to a way or method of doing something.
Ex) "戦術" (senjutsu - tactics) and "策略" (sakuryaku - strategy).Art or craft: referring to a field of study or academic discipline.
Ex) "医術" (ijutsu - medical science) and "法術" (houjutsu - legal techniques).
"師" (shi) has the following meanings.
A person who teaches or guides, such as a teacher or instructor.
Ex) "教師" (kyoushi - teacher) , "医師" (ishi - doctor)A person with specialized skills or knowledge.
Ex) "技師" (gishi - engineer) , "弁護士" (bengoshi - lawyer)A military leader or commander.
Ex) "軍師" (gunshi - military strategist) , "師団" (shidan - division)
Cursed Technique
Cursed Technique: Jutsushiki / 術式
Domain: Ryoiki / 領域
Expansion: Tenkai / 展開
Probably, just like overseas, Japanese don't use the term "Domain Expansion" (領域展開) outside of Jujutsu Kaisen…?
Amplification: Junten / 順転
Blue: Ao / 青
The kanji "順" originally means "in order" or "sequentially."
Reversal: Hanten / 反転
Red: Aka / 赤
The kanji "反" means "reverse" or "opposition."
Hollow: Kyoshiki / 虚式
Purple: Murasaki / 茈
The kanji "茈" is a rare character that most Japanese people don't use.
The commonly used kanji for "purple" in everyday Japanese is "紫(Murasaki)".
I hope this helps you in your Jujutsu Kaisen fandom, even just a little!
Thanks!