Ameba and Protozoan

Ameba noun - Naked freshwater or marine or parasitic protozoa that form temporary pseudopods for feeding and locomotion.

Protozoan and ameba are semantically related In some cases you can use "Protozoan" instead a noun "Ameba".

Protozoan noun - Any of diverse minute acellular or unicellular organisms usually nonphotosynthetic.

Ameba and protozoan are semantically related in minute organism topic. You can use "Ameba" instead a noun "Protozoan".