Ideology, Thought, Idea
noun
When you think and contemplate deeply, you're producing something larger, like an ideology. This means having a group of, or a single larger, thought(s) or idea(s). 思想 refers to the big ideas or beliefs an individual holds about the world and life. It’s often used to talk about one’s thoughts about philosophy, politics, religion, or other such beliefs.
しそう
This is a jukugo word, which usually means on'yomi readings from the kanji. You haven't learned the on'yomi for 思 yet, so here's a mnemonic to help you: All your thoughts and ideas are about sheep (し) right now. You just can't stop thinking about sheep. Are you thinking about sheep right now? What kind of sheep are they?
コウイチの思想にはついていけません。
I can't follow Koichi's thoughts.
あの人、ちょっと思想が強い感じだよね。
That person seems a bit ideological., don't they?
もちろん、内心にどんな思想を持つかはその人の自由です。
Of course, it's each person's freedom to hold whatever ideas they wish in their heart.