Amoeba is a unicellular organism, meaning it is a single cell. It is considered a eukaryotic cell, meaning it has a nucleus and other membrane-bound organelles.

Here's a breakdown:

* Unicellular: Consisting of only one cell.

* Eukaryotic: Having a true nucleus that contains the cell's genetic material (DNA).

So, to summarize, an amoeba is a unicellular eukaryotic cell.