Do not disturb asleepingdog.  Here the underlined word is :

Participle মূলত: তিন প্রকার: 
1. Present Participle. Ex: Do not disturb a sleeping dog. 
2. Past Participle. Ex: This is a book written by Charles Dickens. 
3. Perfect Participle. Ex: Having eaten rice, he went to bed. 

Participle:
- It is the form of a verb that usually ends in "ed" or "ing" and is used as an adjective:
- Participle একই সাথে Verb ও Adjective এর কাজ করে। 

In the sentences "He's sleeping" and "I've already eaten", the words "sleeping" and "eaten" are both participles.

Source: A passage to the English Language by S.M Zakir Hussain