Concept:
A synonym is a word that has the same or nearly the same meaning as another word.
The word:
\[
\text{profusion}
\]
means a large amount or plenty of something.
Step 1: Understand the meaning of profusion.
Profusion means:
\[
\text{abundance}
\]
\[
\text{plenty}
\]
\[
\text{large quantity}
\]
\[
\text{overflowing amount}
\]
For example:
\[
\text{There was a profusion of flowers in the garden.}
\]
This means there were many flowers.
Step 2: Check the options.
Option (A) abundance means plenty or large amount, so it is correct.
Option (B) bleed means to lose blood, so it is not a synonym.
Option (C) blend means to mix, so it is not correct.
Option (D) express means to show or state, so it is not correct.
Hence, the correct answer is:
\[
\boxed{(A)\ \text{abundance}}
\]