actualist

As a noun actualist

is a proponent of actualism.

As a verb actualise is

standard spelling of from=Non-Oxford British spelling|lang=en|actualize.

As nouns the difference between taxonomy and actualist

is that taxonomy is the science or the technique used to make a classification while actualist is a proponent of actualism.

As nouns the difference between actualism and actualist

is that actualism is (philosophy) belief that actuality and existence are co‐extensive: ie, that only actual things exist, that there are not, in addition to the actual, any possibility (possible entities) while actualist is a proponent of actualism.

As nouns the difference between proponent and actualist

is that proponent is one who supports something; an advocate while actualist is a proponent of actualism.

As an adjective proponent

is making proposals; proposing.