The organization threw an epic dinner party yesterday , the bold faced word means-

The word "epic" (বিশেষণ) generally refers to something that is extremely large, extensive, grand, or extraordinary. It is used to describe an event or experience that is remarkable and memorable in its nature.

    
• Amazing (অসাধারণ): This word describes something that is wonderful, exceedingly good, or impressive. An "epic dinner party" means an extraordinary dinner party, which directly aligns with the meaning of "amazing." It is the most appropriate option among the given choices.
    
• Phenomenal (অভূতপূর্ব): This word also expresses a meaning very close to 'amazing,' referring to something extraordinary or outstanding. However, 'amazing' is generally used in a broader sense to express extraordinary delight or wonder, whereas 'phenomenal' often indicates a specific high level of achievement or skill. Nevertheless, these two words are often used interchangeably. In this context, 'amazing' serves as a simpler and more direct synonym.
    
• Ordinary (সাধারণ): This word is the complete opposite of 'epic.' Since 'epic' means extraordinary, 'ordinary' is incorrect.
    
• Colourful (রঙিন): This word typically refers to visible colours or vibrancy. A party can be 'colourful,' but it does not express the core meaning of 'epic.' 'Epic' primarily refers to the overall grandeur, extraordinariness, or impact of the party, not its colours.

Therefore, an "epic dinner party" means an extraordinary or wonderful dinner party, and its most suitable synonym is 'amazing.'