Extremely cowardly' can be the meaning of the word -

• 'Extremely cowardly' can be the meaning of the word - Craven.

Craven (noun), (adjective)

English Meaning: Extremely cowardly (= not brave).
Bangla Meaning: কাপুরুষ; ভীর।

Synonyms: Spineless (মেরুদণ্ডহীন; (লাক্ষণিক) কাপুরুষোচিত), Timid (ভীরু; লাজুক), Gutless, Fearful (ভীরু) Dreadful (ভীতিজনক)। 
Antonyms: Brave (সাহসী; নির্ভীক), Unfearing (শঙ্কাহীন), Courageous (সাহসী), Dauntless (নির্ভীক), Fearless (শঙ্কাহীন)। 

Other Forms: 
- Craven (noun);
- Cravenly (adverb)
- Cravenness (noun)

Example Sentence: 
1. Please check your facts before you accuse us of being craven.
2. It is a craven proposal to raise the white flag.

Source: Website Lecture.