Is the word understand a compound word

No understand is not a compound word. Words like doghouse, bluebird, and treehouse.

It might be said that the word "understand" is a compound word even though we might think it is not. The word is composed by "under" and "stand". it might be said that "under" makes reference to underlying meaning and "stand" to seeing (in order to understand). So it might mean the "underlying meaning that we need to see in order to comprehend what we are seeing".