• The required answer is - To absorb or include something within a more comprehensive category

• Subsume (Verb)
English Meaning: To include something in a particular group and not consider it separately.
Bangla Meaning: কোনো নিয়মের অধীনে কিংবা বিশেষ কোনো শ্রেণির) অন্তর্ভুক্ত করা.

Example Sentences:
- The new theory attempts to subsume all previous models under a single framework.
- Her individual achievements were subsumed into the team’s overall success.
- The broader category of 'mammals' subsumes animals like cats, dogs, and whales.

• 'Thoroughly' is the meaning of the phrase - Out and out.

• Out and out
English Meaning: complete or in every way; in every respect; thoroughly.
Bangla Meaning: সম্পূর্ণরূপে; পুরোপুরি।

• Example Sentence: 
- That's an out-and-out lie!
- The whole project was an out-and-out disaster.

Source: Oxford Learner's Dictionary and Accessible Dictionary by Bangla Academy.

Plurality (noun)
Plural: pluralities

English Meaning:

1. A state or condition where there are many different kinds or types of something; variety or multiplicity.

2. The quality of being plural or made up of more than one; for example, "a plurality of worlds" implies multiple worlds. In grammar, it refers to forms indicating more than one (as in plural verbs).

3. In politics or official context, it can also mean the holding of more than one office at the same time.

Bangla Meaning:
১। [Uncountable noun] বিভিন্নতা বা বহুত্ব; [Countable noun] অনেক সংখ্যক কিছু; (ভোট ইত্যাদির ক্ষেত্রে) সংখ্যাগরিষ্ঠতা বা অধিকাংশ।
২। [Uncountable noun] একাধিক পদ বা দায়িত্ব একসাথে ধারণ করার অবস্থা (বহুপদাধিকার); [Countable noun] যুগ্মভাবে ধারণ করা পদ বা দায়িত্ব (যুগ্মাধিকার)।

Example Usage:

• The plurality of cultures in a cosmopolitan city enriches its identity.

• He was criticized for holding a plurality of offices in the administration.

Sources:

1. Cambridge Dictionary

2. Accessible Dictionary by Bangla Academy