An opinion, in Hebrew, is דעה . Its three letters make up the root of other words as well, such as לדעת – to know, מודעות – awareness, and מדע – science, among others.
My opinion is דעתי . And in my opinion – or, more precisely, according to my opinion, is לפי דעתי .
For example:
לפי דעתי, מה שמציע יוסף זה מוגזם לגמרי.
In my opinion, what Joseph is offering is completely over the top.
There’s also the shorter version, לדעתי – literally, to my opinion.
