means A container or pot in which plants are grown, especially decoratively; also a person or machine that plants seeds.

from From the verb 'plant,' which comes through Old English 'plantian' and Latin 'plantare,' meaning to drive into the ground with the sole of the foot — yes, 'planta' was the flat of the foot, the same root that gives us 'plantar' as in plantar fasciitis. The '-er' suffix simply marks the doer or the thing that does, so a planter is literally 'that which plants,' a sense later stretched from people pressing seeds into earth to the pots holding the earth itself.