The synonym of 'Knowledge' is-

The synonym of 'Knowledge' is- Wisdom.

Knowledge (Noun)
Bangla Meaning: জ্ঞান; অবগতি।
English Meaning: acquaintance with or understanding of a science, art, or technique।

খ) Wisdom (Noun)
Bangla Meaning: জ্ঞানসম্পন্নতা; গভীর ও বিস্তৃত জ্ঞান; প্রাজ্ঞতা; বিজ্ঞতা; বিচক্ষণতা।
English Meaning: accumulated philosophical or scientific learning: knowledge.

Other options:
ক) Ignorance
Bangla Meaning: অজ্ঞতা; অজ্ঞানতা; অনভিজ্ঞান; অনভিজ্ঞতা।
English Meaning: the state or fact of being ignorant: lack of knowledge, education, or awareness.

গ) Fright
Bangla Meaning: আতঙ্কিত হওয়া।
English Meaning: fear excited by sudden danger: alarm.

ঘ) superficial
Bangla Meaning: উপরিতলস্পর্শী; ভাসা-ভাসা; উপর-উপর; অগভীর।
English Meaning: seen on the surface: external.

Source: Merriam-Webster Dictionary, Accessible Dictionary.