In common usage (both before and after pu), "anpa" has the meaning of "place that is down". In pu, "noka" has that meaning instead.
sitelen pona
anpa
location radical + "container"; the latter perhaps from a truncated square for a general object (compare sinpin) or a container (compare poki). for the radical, see also how dots are used in blissymbols; compare blissymbol "below"